(I).   A, B, C, D, E and F are six members of a family.
(II).  One couple has parents and their children in the family.
(III). A is the son of C and E is the daughter of A.
(IV). D is the daughter of F who is the mother of E. Which of the following pairs is the parents of the children ?

Answer: E. None of these

E is the daughter of A and F is the mother of E. So, A is the father of E and hence the husband of F. Now, D is the daughter of F. So, D and E are the daughters of A and F.
Also, A is the son of C. Now, only B remains. Thus, B and C are the parents of A.

Clearly, A and F are the parents of the children D and E.