Best Answer - Chosen by the Asker
(A) You would hear both 'about' and 'on' in spoken English, but 'about' is better and clearer.
(B) Actually, the sentence is correct. In spoken English, you would have to time the pause, since you can't 'say' quotation marks.
It could be interpreted as:
I was on the receiving end of the question. Why is that?
It could be interpreted to mean that you are asking why you were at the receiving end of the question. I would give a short pause, but not too long - otherwise, people might take it the second way.
I was on the receiving end of A. A is almost always something negative. At the very least, A is neutral, not good or pleasant.
In spoken English, prepositions get switched and misused. A native or good speaker will make allowances for this. In formal, written English, the rules are much more strict.
