Given that
1. A is the mother of B;
2. C is the son of A;
3. D is the brother of E;
4. E is the daughter of B.
The grandmother of D is

Answer: A. A

D is the brother of E and E is the daughter of B.
This means that D is the son of B.
Also, A is the mother of B.
So, A is the grandmother of D.
Hence, the answer is (a).