How many sons does X have ?
Statements:
1. Q and U are brothers of T.
2. R is sister of P and U.
3. R and T are daughters of X.
Answer: D
From 1, 2 and 3, we conclude that all P, Q, R, T and U are children of X. Of these, Q and U are male while R and T are female. But the sex of P cannot be determined.