$A$ is the son of $B$; $C$,$B$'s sister,has a son $D$ and a daughter $E$; $F$ is the maternal uncle of $D$. How is $A$ related to $D$?

Pointing to the lady in the photograph,Mrinalini said,"Her son's father is the only son-in-law of my mother". How is Mrinalini related to the lady?

Introducing a man to her husband,a woman said,"His brother's father is the only son of my grandfather." How is the woman related to this man?

$A$ 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. Who is the husband of $P$?

$Q's$ mother is the sister of $P$ and the daughter of $M$. $S$ is the daughter of $P$ and the sister of $T$. How is $M$ related to $T$?

$A, B, C, D, E, F$ and $G$ are members of a family consisting of four adults and three children. Two of the children,$F$ and $G$,are girls. $A$ and $D$ are brothers and $A$ is a doctor. $E$ is an engineer married to one of the brothers and has two children. $B$ is married to $D$ and $G$ is their child. $A$ is the son of $C$. Who is $C$?