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?

$E$ is the son of $A$. $D$ is the son of $B$. $E$ is married to $C$. $C$ is $B$'s daughter. How is $D$ related to $E$?

Rahul's mother is the only daughter of Monika's father. How is Monika's husband related to Rahul?

$Q$ 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 $Q$?

In a family,there are six members $A, B, C, D, E$ and $F$. $A$ and $B$ are a married couple,$A$ being the male member. $D$ is the only son of $C$,who is the brother of $A$. $E$ is the sister of $D$. $B$ is the daughter-in-law of $F$,whose husband has died.
Who is $C$ to $B$?

$A \div B$ means $A$ is the father of $B$,$A - B$ means $A$ is the wife of $B$,$A \times B$ means $A$ is the brother of $B$,$A + B$ means $A$ is the daughter of $B$.
If $P \times R \div Q$,which of the following is true?