A and B are children of D. Who is the father of A? To answer this question which of the statements (1) and (2) is necessary?
1. C is the brother of A and the son of E.
2. F is the mother B.

Explanation:-

A and B are children of D.
From (1), C is the brother B and son of E.
Since, the sex of D and E are not known. Hence (1) is not sufficient to answer the question.
From (2). F is the mother of B. Hence, F is also the mother of A. Hence D is the father of A.
Thus, (2) is sufficient to answer the question.