There are six persons A, B, C, D, E and F. C is the sister of F. B is the brother of E's husband. D is the father of A and grandfather of F. There are two fathers, three brothers and a mother in the group. Which of the following is a group of brothers ?

D is father of A and grandfather of F. So, A is father of F. 

Thus, D and A are the two fathers. C is the sister of F So, C is the daughter of A. 

Since there is only one mother, it is evident that E is the wife of A and hence the mother of C and F. 

So, B is brother of A There are three brothers. So, F is the brother of C. 

Clearly, B and A are brothers. F is the brother of C So, three brothers are A, B, F.