Q is the brother of R; P is the sister of Q; T is brother of S; S is the daughter of R. Who are the cousins of Q ?

The correct answer is E. None of these.

Q is the brother of R, and P is the sister of Q. This means that Q and P are siblings. S is the daughter of R, and T is the brother of S. This means that S and T are siblings.

A cousin is a person who is related to you through your parents’ siblings. Since Q is not related to R’s siblings (P and T), and S and T are not related to Q’s siblings (P), none of the people in the question are Q’s cousins.