Explanation:

- The family consists of six members: P, Q, R, S, T, and U.

- R is the father of S and is married to Q.

- Q has one daughter and one son, so R and Q’s children must be S (son) and perhaps another child.

- T is the sister-in-law of U, who is female.

- U being female and T being her sister-in-law implies that T is either married to U's brother or U is married to T's brother.

- P is the daughter of S, making S P's parent.

- S is not married to T, so T must be married to S's sibling if S is Q's child.

- This makes T, S's sister-in-law.

?? Correct Answer: Option 4, Brother in law