A is the father of B. C is the son of D. E is the brother of A. If B is the sister of C. How D is related to E.

Sister-in-law

Note:

↑ or ↓ ⇒ Upward or downward line shown "generation gap" .

   =    ⇒ Double lines shown "relation b/w Husband & Wife"

   —   ⇒ single line shown "relation between them other than Husband & Wife".

Sister in law, Option B is correct answer.