Correct Answer: P × Q ÷ R

Solution : Let's check the options –
First option: P × Q + R
According to the given expression, the family tree will be as follows –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above family tree, it is evident that Q is the brother of P.
Second option: P + R × Q
According to the given expression, the family tree will be as follows –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above family tree, it is evident that Q's gender is undefined. Q can either be the son or daughter of P.
Third option: P × Q ÷ R
According to the given expression, the family tree will be as follows –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above family tree, it is evident that Q is the sister of P.
Fourth option: Q × P ÷ R
According to the given expression, the family tree will be as follows –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above family tree, it is evident that Q is the brother of P.

So, only the expression in the third option satisfies the relation given in the question. Hence, the third option is correct.