User talk:Heron/2005H2

Synchronous motors

We were discussing on the industrial application of Synchronous motors as power factor correctors and mainly as Synchronous capacitors. Have a look. Your page synchronous motors does not throw light on many aspects especially, the mathematics. Thanks --Davy Jones 02:38, 26 October 2005 (UTC)

when you move a page

please use what links here to check for double redirects and fix them. Plugwash 6 July 2005 22:41 (UTC)

There were quite a lot of them, so I didn't have time to finish. I'm sure I'll get through them all sooner or later. --Heron 7 July 2005 18:05 (UTC)

Tesla and Electrical Engineering

Hi Heron,

Thanks for your additions to the Electrical Engineering article. The new caption for Edison is far more informative than the old one. I have removed Tesla from the article because he is not mentioned in the History section of the article. Please feel free to re-add him to the article preferably with a mention in the History section. Also feel free to edit any other part of the article.

Thanks,

Cedars 13:41, 10 July 2005 (UTC)

My pleasure. I think the History section is looking good now, although it still lacks a global POV. As for Tesla, I don't really care whether his picture is there or not. I think your approach is right - to have pictures of those mentioned in the text, and no others. As I have removed his picture once, and added it once, and been reverted both times, I feel it's time for me to sit back and let others argue it out. I will of course edit other bits of the article if I see the need. --Heron 16:11, 10 July 2005 (UTC)

Crane (machine)

Hi Heron,

I liked your quick response to the anon's request to include some information on the mechanics of cranes. -- Solipsist 23:32, 12 July 2005 (UTC)

Thanks. There was a nice, obvious, inviting gap waiting to be filled, so I couldn't resist. I don't even care if it was someone's homework. :-) --Heron 16:54, 13 July 2005 (UTC)

Peltier-Seebeck effect

Why nablas --> deltas? - Omegatron 16:42, July 20, 2005 (UTC)

Sorry. I misunderstood the article. I have put them all back now. --Heron 18:50, 20 July 2005 (UTC)

Ok. I wasn't completely sure, but thought they were right originally. Gradients vs differences or something... - Omegatron 20:31, July 20, 2005 (UTC)

Rotating Magnetic Field

Heron, could you see if you could look at the rotating magnetic field? It's an engineering topic that should have an article covering it and some [Salsb and William M. Connolley, in particular] seem to not see it as an important concept by itself. The articles "Rotating magnetic fields" and "Introduction to Generators and Motors"; rotating magnetic field, at Integrated Publishing both cover the concerned concept that should be listed in wikipedia. Thanks, 165.201.42.84 19:26, 25 July 2005 (UTC) (PS., is there any other place I can goto to request that the topic be explained? Thanks again)

Hi. I am aware of the arguments that have taken place on Wikipedia on this subject, but there is nothing to say about rotating magnetic fields that isn't covered under "magnetic field", "electric motor" and "dynamo". This includes the articles that you quoted, which are about electric motors. Electric motors are complicated beasts, and come in many different types, and it may well be that our articles on them could be expanded, but I'm probably not the person to do it. If there is any particular fact about magnetic fields that you think we have missed, please explain it to me and I will try to help. If you want to enlist the help of other Wikipedians, Talk:magnetic field is probably the best place to ask. There are some seriously clever people working on that page. --Heron 20:32, 25 July 2005 (UTC)

WikiProject

Hi!

I wonder if this guild is anything that you may benefit from, and in that case, feel invited to sign in :)

Have a good day :)

--Striver 01:35, 30 July 2005 (UTC)

Thank you Striver. You are entitled to your point of view - free speech and all that - but I'm not sure that it is fair to use Wikipedia to promote it. Someone is paying to store and serve all this data, and you and I are entitled to use these facilities only to further the aims of Wikipedia, not to pursue our own political ends, whether they be justified or not. Setting up a "guild" based on a prejudged view of world events seems to me to be contrary to the idea of NPOV. I would recommend setting up your own website. Good luck in your investigations. Regards, --Heron 09:27, 30 July 2005 (UTC)

Heat Sensistive 'relay'

Yes , I think this could be moved to another page. Would you care to oblige??Light current 23:54, 5 August 2005 (UTC)

I would gladly have done so, but Meggar has beaten me to it. --Heron 10:42, 6 August 2005 (UTC)

electrometer

Does an Talk:Electrometer measure charge, electric field, or voltage? - Omegatron 16:12, August 7, 2005 (UTC)

The Penguin Dictionary of Electronics says either voltage or charge, although this instrument measures current and charge. Here is a basic instrument that reads only volts. This article by "Mr Static" says that an electrometer "can be run as a charge meter (high capacitance) or as a static voltmeter (low capacitance)". (By the way, Mr Static's web pages are a goldmine of information on electrostatics.) The general picture seems to be that an electrometer is any electrical measuring instrument that works on electrostatic rather than electrodynamic principles. E-field meters are a special case: although they are fundamentally electrometers, they are so specialised that they tend to have other names, including my favourite, the "E-field mill".

By the way, the statement at the beginning of the electrometer article that "electrometer [is] also known as an electroscope " is not quite true, since electrometers are accurate quantitive devices and electroscopes are either roughly quantitative or merely indicative. --Heron 18:53, 7 August 2005 (UTC)

Yes, I have seen all three definitions online. It seems that a charge measurement would be something like "this metal sphere has x coulombs of excess negative charge", though, and wouldn't be something you could measure by holding an object nearby.

Yes, I've read Mr. Static's pages a lot lately (and asked him if he'd like to contribute!)  :-) - Omegatron 22:25, August 7, 2005 (UTC)

Yes, I thought about contacting him, but then I thought, he probably doesn't write this stuff for nothing. I hope you can prove me wrong.

Yeah, it's doubtful. I'm probably not the best wikivangelist, either. We should have a group of "templates" for sending out in emails to different categories of people with good arguments persuading them to contribute. - Omegatron

I can see why charge measurement is difficult. However, the Millikan oil drop experiment is an example of a non-contact method for measuring free-floating charged objects (but only if you know their mass). Arguing from symmetry, it ought to be possible to measure a fixed object by making your measuring instrument float. There are probably lots of kinds of "charge measurement" that all require different measuring techniques. --Heron 14:12, 8 August 2005 (UTC)

True, I'm not saying it's not possible to measure the charge on an object. I'm just saying that a device that changes measurement as you move it closer to or farther away from an object is definitely not measuring charge, where charge = excess charge on a single object. It would have to be something that you contact to an object and it measures the excess charge on the whole object. I'm not even sure how that would work on an insulator. So it's measuring voltage or electric field or something. - Omegatron 14:52, August 8, 2005 (UTC)

OK. Here's a summary of what I've learned so far.

1. An electrometer is a voltmeter with an extremely high input impedance. Old electrometers produced a visible displacement of a moving part, and were called electroscopes or arbitrary electrometers [1]. Later models measured the force or torque produced by electric fields, gave a numerical output, and were called absolute electrometers. Modern absolute electrometers are electronic, using first vacuum tubes and then op-amps as the detectors.
2. To measure charge, you can use an electrometer to measure voltage and then use Q=CV [2]. This can only measure the charge dumped on to the electrometer, not the charge on some distant object.
3. If you can measure charge, then you can integrate it w.r.t. time to get current. This is how some current-measuring electrometers work [3]. It's called an integrating transimpedance amplifier (circuit here).

I think I've now got a clear enough understanding to be able to start editing articles, but if you want to go first, don't let me stop you! --Heron 19:46, 8 August 2005 (UTC)

current and voltage sources

What's your opinion on a voltage divider being classified as a voltage source, and a resistor being classified as a current source? - Omegatron 14:54, August 8, 2005 (UTC)

It depends on whether you're talking about an ideal source or a practical approximation to one, I suppose. The articles should say that in circuit theory the terms "voltage source" and "current source" have an implied "ideal" before them, whereas in circuit design they often refer to very poor approximations of those ideals. The voltage source symbol (a circle) and the current source symbol (two overlapping circles) by definition represent the ideal forms, whereas electronic components are always non-ideal (obviously). I notice that there has been some heavy editing going on recently on those articles, so I'll have a quick scan of them to check that they haven't gone all weird. --Heron 20:15, 8 August 2005 (UTC)

Yeah. I should have linked to the talk pages, I guess.

The approximation to an ideal source is very poor, and it seems that by that logic, anything could be considered a voltage source through a Thevenin conversion. I would argue that only things that make a reasonable (whatever that means) approximation to an ideal source over a certain range of conditions should be classified as sources. Since a resistor only approximates an ideal current source for an infinitesmal range of conditions (at a specific load resistance and specific voltage it will give the correct current, but not if either varies) I wouldn't classify it as a source. But I'm willing to budge. - Omegatron 20:51, August 8, 2005 (UTC)

Having read the talk pages for those articles, I see what all the fuss is about. Like you, I'm not too happy with the conflation of near-ideal sources with dodgy resistor networks, but the argument seems to be one of degree. How about this:

A voltage source is a device that sources current into a load so that the voltage across its terminals is largely independent of the load impedance over a given range of load impedances. Voltage sources range in performance from 'ideal' (useful for calculations, but but nonexistent), through 'fairly good' (such as voltage regulators, monopolar generators and lead-acid batteries) down to 'crap' (such as voltage dividers). Whether or not a particular device can be considered a voltage source depends on the application.

A current source is a device that sources a largely constant current into a load regardless of the voltage across its output terminals over a given range of voltages. Current sources range from 'ideal' (useful for calculations, but nonexistent), through 'fairly good' (such as op-amp current sources and Van de Graaff generators and photodiodes) down to 'crap' (such as large resistors connected to constant high-voltage sources). Whether or not a particular device can be considered a current source depends on the application.

In summary, there is a continuum from 'ideal' to 'crap', rather than a threshold below which a device is not a voltage/current source. Do you think this view might please everybody? --Heron 21:07, 8 August 2005 (UTC)

Mostly agree. We should move this talk over there. - Omegatron 03:01, August 9, 2005 (UTC)

OK. I'm watching both those articles. The same goes for electrometer. --Heron 08:34, 9 August 2005 (UTC)

Analog-to-digital converter and sampling frequency of digital oscilloscope

What is untrue about digital osciloscopes being able to take 50 MS/s? ([4]) I admit there are faster and slower ones, and few well funded labs far mor faster rigs, but ~50M is what you buy in a shop. My roommate's one can do 30 MHz. --Alvin-cs | Talk 21:22, 14 August 2005 (UTC)

Your statement "Digital oscilloscopes usually acquire 50 milion samples per second" meant that most DSOs have exactly that sampling rate. It may not be what you meant, but it's what you said, and it's not true. A truer statement would be that "DSOs in common use have a wide range of maximum sampling rates, from a few tens of megasamples per second for cheap models, through mid-range models at around 50 to 100 megasamples per second, to one or two gigasamples per second for the most expensive." If you want to go into more detail than that, it would perhaps be better to add it to the oscilloscope article. I know that I'm picky, but then so are all other Wikipedians. Please don't be put off :-) --Heron 19:40, 18 August 2005 (UTC)

Sidam

I just posted the difficulties with electromagnetic induction on Wikipedia_talk:WikiProject_Physics, which should be sufficient to deal with that particular article. I'm not particularly familiar with how RfC's work, but in principle I am willing to countersign--it seems like User:Sidam has been a continuous problem for some time now. -- SCZenz 19:15, 18 August 2005 (UTC)

Thanks. I'll wait to see what happens on WikiProject Physics before I go any further. I don't know how effective RfCs are. --Heron 19:44, 18 August 2005 (UTC)

Im getting rather tired of Sidam now, so I think something should be done pretty soon!--Light current 22:46, 24 September 2005 (UTC)

I know. I'll support a ban, and block him myself, but only after all the necessary procedures have been followed. User:SCZenz is currently working his way through the list of official warnings, which Sidam is ignoring. After that, I think we'll have to do a survey of users for and against a ban. I doubt that anyone will be against, but you never know. --Heron 12:02, 25 September 2005 (UTC)

Someone should check if He actually understands English tho'. If not we may need to issue warnings in Russian--Light current 13:31, 25 September 2005 (UTC)

That's not our problem. If he wants to contribute to the English-language Wikipedia, he will have to defend himself in English. --Heron 14:01, 25 September 2005 (UTC)

Scientific method

Nice copyediting on this article! Mamawrites 16:08, 21 August 2005 (UTC)

Thanks. I'll add it to my watchlist. --Heron 17:20, 21 August 2005 (UTC)

Dayak

It looks like you wrote the first stub for the Dayak article, in whivh you stated that the name means 'upstream'. Aren't you confused with 'dahulu' (which also means that)? Also, you state that they were cannibals, but I've read a fair bit about them and never heard of that. They were (and occasionally still are) headhunters. But there were (and still are) cannibals in New Guinea. Maybe that caused the confusion? DirkvdM 09:55, 24 August 2005 (UTC)

On the origin of the name, this article says it means "inland", which, in the context of a small island, I suppose is synonymous with "upstream". Perhaps it means both.

Small island? It's the third biggest island in the world! Do I detect an irony I don't get? DirkvdM 12:07, 24 August 2005 (UTC)

No, you detect my ignorance. Sorry. --Heron 13:24, 24 August 2005 (UTC)

Here's a BBC report that mentions "evidence of cannibalism", but I'll try to find something less equivocal. I remember reading that the Dayak practice was to cut off the head, and remove and eat the heart (here's another BBC report that mentions removal of the heart). The main reference I used to write the article was a blood-curdling piece about the Dayaks in Granta magazine, which I will try to find for you. I can assure you that I wasn't thinking of New Guinea. --Heron 11:54, 24 August 2005 (UTC)

I already removed the cannibalism bit (along with several other edits), but if you can find good sources just put it back. But unless you (or I) can find a source that also mentions it for times before transmigrasi, I wouldn't call it 'resurgence'.

OK, I'll keep looking for evidence (or maybe I should have a rest from this morbid search and write about flowers and bunny rabbits instead!). However, it's easy to find an old reference to cannibalism - it's mentioned in a 1911 encyclopedia [5] (paragraph 5). I think that predates transmigrasi by several decades. --Heron 13:24, 24 August 2005 (UTC)

Well it does. But I've got my doubts about this source. But that has partly to do with a paternalising stance. Like calling the Punan the fifth and lowest form of Dayaks who are still nomadic and ignorant of agriculture. That stance doesn't need to have interfered with acuracy, but calling the Punan Dayaks doesn't give me too much confidence in the article. And what to think of 'houses made of bamboo'? For the rest I don't see too many inaccuracies. So I'm not sure, but I really want to know this. I've Googled the combination of the two terms ("dayak cannibalism") and there are quite a few writings about this, a lot of hogwash, and some quoting each other, but some of it seems fairly reliable. But nothing conclusive. The most reliable source I found is [6]. But they seem too much bent on defending the Dayak to promote the island.

By the way, if you search for "dayak cannibalism encyclopedia" you'll see that most online encyclopedias simply copy Wikipedia (loads of them, often old copies - lazy bastards!), and considering we two seem to be the only ones discussing this I'd say we have a huge responsibility in educating the world! :) .

And by another way, flowers have a habit of getting decapitated too, and even dried (like shrunken heads). And what about bunny rabbits around Christmas? :) . DirkvdM 18:57, 24 August 2005 (UTC)

I agree with you about the 1911 encyclopedia. Statements like "The Dyak is decidedly intelligent..." don't give you much confidence, but all research of that era was probably in the same style. I wonder if you have access to any old Dutch-language works on the subject? The Dayakology website obviously emphasises their own good side, but to my surprise does actually admit the horrors we are talking about. I Googled for "headhunters OR headhunting site:dayakology.com" and found "The Role of Adat in the Dayak and Madurese War", which begins by describing "headhunting" and "cannibalism" (their quotation marks) as myths, but then goes on to explain why they do it! It's a long read, I'm afraid, but the facts are all there. I am tempted to laugh at what seems to be their hypocrisy ("We don't do it. Well, all right, we do, but the spirits make us do it", etc.), but then I have to be fair and admit that every culture goes to extreme lengths to justify its own crimes. They kill with machetes; we do it with bombs. Sweet dreams. --Heron 19:54, 24 August 2005 (UTC)

For which 'we' now have the excuse of terrorism (no, really, it's the others who are the terrorists...). I wonder if in your remark you meant to refer to cannibalism as a crime. I came across a few discussions on the internet in which it seemed that people thought headhunting was bad but cannibalism was really atrocious. I've never really understood this. I myself couldn't care less if people ate me after they kill me, but I would mind getting killed in the first place. Anyway, about the article. The way it is presented may look funny to us, but probably has to do with the way Dayaks talk things through. As in many parts of the world, first you establish a friendly atmosphere and then slowly you come down to business. Which certainly has its charms to say the least. Thing may start more slowly, but if in the end it achieves more consent then in long run it may turn out to be a faster matter to resolve things. I wonder if it was written by Dayaks directly, though, the English is too native for that (eg "... binary oppositions that establish conceptual order?"). I suspect the cooperation of an anthropologist. Note also that they speak of 'colonialism, both past and present', which is a point rarely mentioned. The Dutch colonists have been replaced by Javanese ones. Anyway, I suppose we can establish that there has been cannibalism among Dayaks, though to a small extent. I've put it back in the article, but I'm not sure about the wording. I don't entirely follow the reasoning in the Dayakology article. DirkvdM 08:22, 25 August 2005 (UTC)

Yes, I did imply that cannibalism and headhunting were crimes, but I hadn't thought very hard about it. I suspect that they're not crimes in the legal sense, at least not in secular states. It just seemed to me that it was a disrespectful way to treat the deceased. Many cultures like to bury their own dead in one piece. The headhunter or cannibal might claim that, in his culture, the practice is a mark of respect for the dead warrior, but this isn't fair if the dead man was from a different culture.

Anyway, I'm glad we have reached a consensus (for now) on the article. If we need to discuss the subject any further, shall we do so on the Talk:Dayak page? --Heron 12:19, 25 August 2005 (UTC)

Yes, I was thinking that too. Just one more thing to round this off here. I was only talking about cannibalism. The way they headhunt is something different because that's the way they kill their enemy (at least, I've always assumed that). Which of course is not ok. DirkvdM 18:34, 25 August 2005 (UTC)

Transmission line

The title of this page is very missleading and really does not deal with what I think the average person would expect when he searches for transmission line. I would expect Electric power transmission. I had to do a lot of hunting to find it. Do you think some editing, renaming, or something should be done. This is out of my pay grade.Phil 22:20, September 4, 2005 (UTC)

Yes, I can see why you find it inconvenient. Perhaps our article is aimed too much at specialists. I will try adding a comment at the top of the page for the benefit of people who are expecting the mains power article. --Heron 17:09, 5 September 2005 (UTC)

Titmice

'"Perhaps they said 'There's a titmouse. Oh look, there's another one.'"'

Brilliant. --Nathew

I use the same technique for the plural of mongoose. :^) --Heron 20:59, 10 September 2005 (UTC)

Sorry

Sorry about that, Heron. I was just trying to tidy up the page. Anyway its OK now.--Light current 19:17, 11 September 2005 (UTC)

No problem. By the way, I have raised another issue on your Talk page. --Heron 19:37, 11 September 2005 (UTC)

Interesting discussion

An interesting discussion has just broken out on Talk:Capacitor. Take a look, you may be interested--Light current 23:21, 11 September 2005 (UTC)

WikiProject Electronics

I am wondering if we should start a WikiProject for Electronics. What do you think? — Omegatron 00:22, 15 September 2005 (UTC)

That's an interesting suggestion. I haven't worked on a Wikiproject yet, so I'm not sure what it would entail, but I just went off and read some of the Wikiproject:Physics stuff. Here are my first thoughts:

• Pros

1. It will give us somewhere to discuss generalities without cluttering the talk pages of node-level articles.
2. It might help to enforce consistency of facts and presentation within the electronics articles.
3. The statement of goals at the beginning of the Wikiproject would help us to decide on, and then stick to, a common purpose.

• Contras

1. Some effort will be necessary to adminster the project. Judging by the large number of contributors to this subject, this may not be a problem.
2. Contributors (including you and me) might get distracted by the bureaucratic work and spend less time actually writing articles.
3. I'm not sure yet whether the existence of a Wikiproject makes a subject more or less accessible to newbies. I wouldn't like to do anything that creates a barrier to new contributors.
4. Have you thought about where to draw the boundaries of the subject? As I understand it, electronics is a branch of physics, whereas electronic engineering is a branch of electrical engineering which is a branch of engineering. Did you intend the project to cover both the physics and the engineering?

I suggest we could start by writing a provisional intro page based on the template in Wikipedia:WikiProject best practices. If this gets other people interested, then the project might go forward. If people are indifferent then the project will stall, which would be better than going ahead without enough support. --Heron 19:31, 15 September 2005 (UTC)

The project was already started by another user, though I think we can consider it a prototype. You should bring up these concerns on the talk page. — Omegatron 13:40, 22 September 2005 (UTC)

I'm happy with what has been done on the project so far. Perhaps I'll see you there. --Heron 17:00, 22 September 2005 (UTC)

Pune

Thank you for your contribution at Pune. Please keep it up!!! - P R A D E E P Somani (talk) Feel free to send me e-mail.

New Engineering Wiki

Engineering Wiki is a wiki entirely dedicated to collecting information about Engineering. I invite you to join this wiki.

Hoo Peninsula

Hi Heron

Hoo Peninsula is looking great. In fact, a lot of the material is more detailed for this overview than for the individual villages, particularly Cooling. How would you and Faedra (who seems to be a major contributor) feel if I pulled some of the detail out of the Hoo Peninsula page and into those for the separate villages (with a X-ref of course)?

I'm new to Wiki, and will start a separate Cooling page as soon as I learn how! In the meantime, there I've been adding Cooling material to Cliffe, where it already had a mention.

All advice gratefully received! JackyR 23:34, 4 November 2005 (UTC)

I like your suggestion. Anyway, I'm not a major contributor to that article, so don't worry about consulting me in future. Best wishes. --Heron 13:23, 5 November 2005 (UTC)

Hi, thanks for doing the moves I've only been talking about... In fact, I am re-writing/referencing Cooling (off WP), so I'll plug that in from scratch when I'm (eventually) done. Everything else, Wiki WYSIWYG... Have a lovely Xmas :-) JackyR 17:56, 22 December 2005 (UTC)

Glad you like it. Best wishes to you, too! --Heron 18:39, 22 December 2005 (UTC)

SWER

I'd appreciate if you could make a dumbed-down explanation of the "earth return" part of SWER for someone fairly ignorant of electrical engineering. How literal is that term? (Although C J Cowie is already answering my question, I figure that seeing a differently phrased answer couldn't hurt.)

It is literal. The current goes back to the high-voltage transformer, which may be hundreds of km away, through the earth. I'll have a look at the article you mentioned to see if I can make any improvement. --Heron 21:35, 13 December 2005 (UTC)

Revert

Hi, this is with reference to your revert of an edit by User:Jengod on List of misleading food names. You have used the revert button, which I feel, is not justified in this case as he was not committing vandalism. I just wanted to bring this to your attention as it may have been an oversight on your part. --Gurubrahma 14:24, 29 December 2005 (UTC)

Use of the revert button is not an accusation of vandalism. The edit in question was a joke that did not belong in the article, so I removed it. Perhaps you mean that I should have explained my reason in the edit summary, in which case I admit to being lazy on that occasion. --Heron 21:11, 29 December 2005 (UTC)

Electricity

I don't believe that is appropriate to define electricity as synonymous with electric charge. It seems to me that: "Electricity is a general term applied to phenomena involving a fundamental property of matter called an electric charge." is a good definition. I don't think electric power is a phenomenon but rather a technological application of electromagnetic phenomona. --C J Cowie 18:37, 29 December 2005 (UTC)

This is difficult. My definition errs on the side of strictness, while IMO yours is so broad that it fails to define the term. I could conclude from your version that chemistry is electricity, since all chemical reactions "involve" electric charge, yet chemistry is not mentioned in the list of phenomena in the article. I suspect that we can define the term only by listing the specific phenomena that it covers. I shall tweak the definition in your direction, so see what you think.

I agree with your second point. I remember thinking exactly that as I was editing the article, but then the devil made me press the "save" button. --Heron 20:32, 29 December 2005 (UTC)

Thank you. I like the new definition. --C J Cowie 21:11, 29 December 2005 (UTC)

Power Factor

Re your To-do list, you may have noticed that I added a "power triangle" vector diagram to Electric power. --C J Cowie 21:03, 29 December 2005 (UTC)

Well done! I like To-Do lists that complete themselves. --Heron 21:22, 29 December 2005 (UTC)

Today's selected anniversaries

Wouldn't the flag on the selected anniversaries for December 31 look a little better if you added a border around it? {{border}} Thanks. — Alex 23:02, 31 December 2005 (UTC)

Link: Wikipedia:Selected_anniversaries/December_31

OK, as it's you. I tried it. --Heron 11:47, 1 January 2006 (UTC)