A family consists of a father, a mother, and three children: P, Q, and R. P is the eldest and is studying medicine, Q is studying law, and R is the youngest. If the mother is a lawyer, who is the father?
In a family, there are four members: A, B, C, and D. A is the grandfather of C, B is the mother of C, and D is the sister of C. What is the relationship of A to D?