$A$ and $B$ are brothers. $C$ and $D$ are sisters. $A$'s son is $D$'s brother. How is $B$ related to $C$?

$A$ 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. Which of the following are two married couples?

$(i)$ In a family of six persons $A, B, C, D, E$ and $F$,there are two married couples.
$(ii)$ $D$ is the grandmother of $A$ and mother of $B$.
$(iii)$ $C$ is the wife of $B$ and mother of $F$.
$(iv)$ $F$ is the granddaughter of $E$.
Who among the following is one of the couples?

$Q$ is the brother of $R$; $P$ is the sister of $Q$; $T$ is the brother of $S$; $S$ is the daughter of $R$. Who are the cousins of $Q$?

$A$ 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. Which of the following are the two married couples?

Five persons namely $P, Q, X, Y,$ and $Z$ are sitting in a park. $P$ is the mother of $X$,who is the wife of $Z$. $Y$ is the brother of $P$,and $Q$ is the husband of $P$. How is $X$ related to $Q$?