Pointing to a boy,Seema said,"He is the son of my grandfather's only child". How is the boy related to Seema?

There are six persons $A, B, C, D, E$ and $F$. $C$ is the sister of $F$. $B$ is the brother of $E$'s husband. $D$ is the father of $A$ and grandfather of $F$. There are two fathers,three brothers,and a mother in the group. Which of the following is a group of brothers?

$A$ is the father of $C$,and $D$ is the son of $B$. $E$ is the brother of $A$. If $C$ is the sister of $D$,how is $B$ related to $E$?

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?

Pointing to a photograph,Sachin said,"She is the grandmother of my father's sister's son." How is the woman in the photograph related to Sachin?

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