Nonrestrictive clauses are those which are set off by commas from the rest of the sentence. I'd choose the answer <u>which<em /></u> as the correct one, because yet introduces independent sentences, and that and while introduce restrictive clauses. For example: The price, which was very high for me, was quite reasonable for Frank.<u />
I think it depends on who makes more money. If I was a well paid doctor and my roommate was on the street selling rocks, I wouldn't mind paying the bills.
