(i) In a family of six persons A, B, C, D, E and F, there are two married couples.
(ii) D is grandmother of A and mother of B.
(iii) C is wife of B and mother of F.
(iv) F is the grand daughter of E.

Which of the following is true ?

A. A is brother of F.
B. A is sister of F.
C. D has two grandsons.
D. B has two daughters.
E. None of these
Answer: A . None of these

Justification: The sex of A is not known.
So, neither (a) nor (b) is definitely true.
Clearly, Dis the grandmother of A and F.