nearly identical :-)

MUSCOVITEit depends on what it is

It depends on/upon what it is. is the correct one.

Prajwal

Omission of the preposition is sometimes possible in casual speech.

A: Do you want to come along for the ride?
B: Oh man, I don't know. It depends where you're going.

I think this usage might work with "what", where" and possibly some other words.

IvanhrOmission of the preposition is sometimes possible in casual speech.

Ah! yes.

Prajwal

I think the use of "on" is necessary in your sentence .

English is vast and disorganized, like the British Empire was. Not only are there several varieties and a thousand dialects, it is constantly changing. My answer is just my opinion, based on a lifetime of reading and speaking though it may be.

Sentence a) is common enough, but it is non-standard and of low register. (But be aware that practically every time I say that, somebody quotes Sha

enoonuse "on", no one will notice. If you do not use "on", some people will notice and laugh up their sleeve

Perhaps, but it is common enough to have made its way into a dictionary. http://

Here is the usage note for "depend" from the Oxford dictionary. I think it is particularly helpful because it covers all of the (correct) opinions expressed above.

"In informal use, it is quite common for the on to be dropped in sentences such as it all depends how you look at it (rather than it all depends on how you look at it), but i

@Ivanhr:

I said it was common.

Don't think that everything that has made into some dictionary somewhere is automatically standard English and can be used in all situations. I have seen this before from Macmillan; they seem to be quite descriptivistic. Some dictionaries see it as their duty to report what people are saying and writing even if those people are journalists