Pointing to a photograph,a woman says,"This man's son's sister is my mother-in-law." How is the woman's husband related to the man in the photograph?

$A$ family consists of six members $P, Q, R, S, T,$ and $U.$ There are two married couples. $Q$ is a doctor and the father of $T.$ $U$ is the grandfather of $R$ and is a contractor. $S$ is the grandmother of $T$ and is a housewife. There is one doctor,one contractor,one nurse,one housewife,and two students in the family. What is the profession of $P?$

Pointing to a photograph,Vipul said,"She is the daughter of my grandfather's only son." How is Vipul related to the girl in the photograph?

Introducing a man,a woman said,"His wife is the only daughter of my father." How is that man related to the woman?

$A$ is the brother of $B$. $B$ is the brother of $C$. $D$ is the father of $A$. Based on these three statements,which of the following statements cannot be definitely true?

$P$ is the brother of $Q$ and $R$. $S$ is $R$'s mother. $T$ is the father of $P$. Which of the following statements cannot be definitely true?