Correct Answer: N is the brother of R’s father

Solution : Given:
P # Q ⇒ P is the husband of Q
P + Q ⇒ P is the son of Q
P @ Q ⇒ P is the brother of Q
P % Q ⇒ P is the father of Q
P & Q ⇒ P is the mother of Q
P × Q ⇒ P is the wife of Q

As per the given information, the family tree will be as follows –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure.

Now, let's check the given options –
First option: M is the brother of R – From the above family tree, it is evident that M is the wife of R's cousin. So, this option is incorrect.
Second option: M is the daughter-in-law of R – From the above family tree, it is evident that M is the wife of R's cousin. So, this option is incorrect.
Third option: O is the daughter of Q – From the above family tree, it is evident that O is the brother's son of Q. So, this option is incorrect.
Fourth option: N is the brother of R’s father – From the above family tree, it is evident that N is the brother of R's father. So, this option is correct.

Hence, the fourth option is correct.