Concept:Identify U's father as the husband of the only mother, V, and eliminate impossible candidates using the given blood relations.Explanation:V has a husband, so V is female. There is only one mother in the family, so V must be the mother of U and X. Therefore, U's father must be V's husband. Y is the brother of V's husband, so Y cannot be the husband. X is the sister of U, so X cannot be the father. W is the grandfather of U, so W cannot be the father either. Thus, among the given persons, only Z remains. Also, W is the father of Z, and W is the grandfather of U, confirming that Z is the parent of U.