Pointing to a girl in the photograph,Amar said,"Her mother's brother is the only son of my mother's father." How is the girl's mother related to Amar?

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

These questions are based on the following information. Study it carefully and answer the questions.
$(i)$ $A \times B$ means $A$ is father of $B$.
$(ii)$ $A \div B$ means $A$ is daughter of $B$.
$(iii)$ $A + B$ means $A$ is sister of $B$.
$(iv)$ $A - B$ means $A$ is husband of $B$.
$D$ is brother of $B$. $M$ is brother of $B$. $K$ is father of $M$. $T$ is wife of $K$. How is $B$ related to $T$?

If $A+B$ means $A$ is the mother of $B$,$A \div B$ means $A$ is the brother of $B$,$A \times B$ means $A$ is the son of $B$,and $A-B$ means $A$ is the daughter of $B$,which of the following means $C$ is the niece of $D$?

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 $Y$ related to $Q$?

In a village of Bastar district in Madhya Pradesh,only two types of people live who belong to a tribal class. The first type is known as class $A$,while the other is known as class $B$. In that village,there is no other type of person except these two. The activities of both types of people are governed by perfectly patterned norms of social behaviour. Each person of the tribe has to obey the norms. They are rigid about this.
As far as marriage is concerned,the following norms are to be followed:
$(A)$ The people of class $A$ cannot marry any other member of their own class,though they can marry members of class $B$.
$(B)$ After being married,each male member ceases to be a member of that class in which he was born but automatically,he becomes the member of the other class to which his wife belongs.
$(C)$ As far as females are concerned,they remain the members of their own class after being married.
$(D)$ On his birth,the child automatically becomes the member of his mother's class.
$(E)$ When any male member becomes a widower or divorcee,then he again belongs to the group in which he was born.
$(F)$ Nobody can marry more than one person according to social laws.
Which of the following marriages is not permissible according to the social laws?