Can someone advise which of the following is correct?

"___________ car have you borrowed, Tom?" asked John.
1) Whom
2) Which
3) Whose
4) Who

One more question - can the kids begin a sentence with "And", "Because" or "But" in their composition writing?

Thanks!

The answer is Whose.

It is not advisable to start sentences with those words which are conjunctions.

Hi
I am not too sure ,but I think that the answer might be either whose or which
As for the second Question,I agree with Tammy

The answer can be both which and whose
because which could be used when one is selecting
an object among various objects, which is applicable here.
As for whose, Tom could be choosing from a few friends'
cars. Therefore, both options are applicable.

Most teachers do not encourage pupils to use
those conjuctions for comprehenision as pupils
often tend tomake grammatical errors in their answers.
Putting "Because" at the start of each sentence would not be wise
as the pupil would need a complete sentence. "But" would
usually not be necessary. It would be unusual to begin a sentence
with "but". Likewise for "As", except for in special cases:
eg.
As John had already crossed the bridge, he was not injured.

However, it would be better to put it as:
John had already crossed the bridge, and therefore, he was not injured.

I hope you find this useful.