A and B are brothers. C is sister of A and D is brother of E. E is daughter of B. Then who is the uncle of D?

Uncle of D is A.

-- James

James your answer is correct. Let me explain how I arrived at this solution so that it may benefit others in this discussion. The way to approach such problem is to write the problem in short words and represent in a convenient diagram say in this problem:
A- Brother of B
E- Daughter of B
D - Son of B
which can be represented as
A
/ \
C-Sister B
/ \
E-Daug D-son

So uncle of D is A.

Absolutely Right. A is Uncle of D. It's a tricky one

Ans:- A

boy gal
------------------------
A ----- > C
B ------>
D ------> E and E is the daughter of B and and B are two brother