USED in FAMILY tree diagram:According to the information given in the question:1. A is the elder son of C and the FATHER of D ⇒ A is elder son of C means C has more than one son and A is father of D. 2. C is the mother-in-law of B, B is not the wife of A ⇒ From these statements, we can say that B is wife of younger son of C.Family tree diagram: A is the father of D, C is the mother of A and B is the sister-in-law of A.So, B is the AUNT of D.Hence, "Aunt" is the CORRECT answer.