Explanation:

Let's break down the logic step by step:

- R is S's only sibling and is P's son. So, P is father/mother of R and S.

- Q is S's mother. Therefore, P must be the father.

- T is the mother of V and the sister-in-law of S. S’s sibling is R, so T is married to R (as T is sister-in-law of S).

- V, the child of T, is called nephew of S, so R (S's brother) and T (R's wife) have son V.

- U is S’s wife and has no sibling.

Now, the question: How is T related to R?

- T is married to R (as the mother of his child V, and the sister-in-law of S).

Option 3: Wife is correct.

Options explained:

- Sister-in-law: T is S’s sister-in-law, not R’s.

- Sister: No evidence supports T being R's sister.

- Wife: T is R's wife.

- None of these: Not needed.

- Cannot be determined: Not applicable.