1.  Questions : How is  M related to N ?
Statements :

I.  P,who has only two kids, M and N, is the mother-in-law of Q, who is sister-in-law of N.
II. R,the sister-in-law of M,  is the daughter-in-law of S, who has only two kids, M and N.

A. I alone is sufficient while II alone is not sufficient.
B. II alone is sufficient while I alone is not sufficient.
C. Either I or II is sufficient.
D. Neither I or II is sufficient.
E. Both I or II are sufficient.

Answer: Option A

Explanation:

From I, we conclude that P is the mother is M and N, while Q is the daughter-in-law of P and sister-in-law of N. Thus Q is M's wife and hence, M is N's brother . From II, we conclude that M and N are the children of S. Also, R is the daughter-in-law of S and sister-in-law of M. So, R is N's wife and thus, N is M's brother. Hence, M is either brother or sister of N.