1.  Question: B is brother of A. How is A related to B ?
Statements:

I.  A is the sister of C.
II. E is the husband of A.

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 nor II is sufficient
E. Both I and II are sufficient

Answer: Option C

Explanation:

B is A's brother means A is either brother or sister of B. Now each one of I and II individually indicates that A is a female, which means that A is B's sister.