Let's establish the relationships: - E is the son of A. (A is E's parent) - D is the son of B. (B is D's parent) - E is married to C. (C is E's wife) - C is B's daughter. (B is C's parent)From "D is the son of B" and "C is B's daughter", we know that B is the parent of both D and C. Therefore, D and C are siblings. We also know that C is E's wife. D is C's brother. Since C is E's wife, D is the brother of E's wife. The brother of one's wife is one's brother-in- law.