Question

A and B are two events. Which statement about the conditional probability is true?

Answer 1

The answer 
by using fundamental definition
The conditional probability of event B given event A is P(B|A)=P(A and B)/P(A) when two events are not independent.
so the only true answer is A, because P(B|A)=P(A) if A and B are independents
(definition)

Answer 2

The answer is A. I just took the quiz.