We need to determine the father-in-law of Q.
- Step 1: Identify relationships: P is married to Q, so P and Q are husband and wife. S and T are their daughters (females).
- Step 2: Determine R’s role: R is P’s only son, so R is the son of P and Q (male).
- Step 3: Analyze U’s role: U is Q’s mother-in-law, so U is the mother of Q’s spouse (P). Thus, U is P’s mother (female).
- Step 4: Find father-in-law: Q’s father-in-law is P’s father. The family has six members (P, Q, R, S, T, U), and no male is identified as P’s father.
- Step 5: Check options:
- (a) R: Son of Q, not father-in-law.
- (b) S: Daughter, not male.
- (c) T: Daughter, not male.
- (d) None of these: Correct, as P’s father is not liste(d)
Thus, the answer is d.