A family consists of a mother, a father, and three children: P, Q, and R. P is the eldest and is studying medicine. Q is studying engineering and is younger than P but older than R. What is R's field of study?
A family consists of four members: A, B, C, and D. A is the mother of B. C is the father of B and D. D is the sister of B. What is the relationship between A and D?
A family consists of a grandmother, a mother, and two daughters. If the grandmother's name is Mary, the mother's name is Sarah, and the daughters are named Anna and Lisa, who is the mother of Anna?