Correct Answer: A ÷ B + C

Solution : Given:
P + Q means that P is the mother of Q.
P ÷ Q means that P is the father of Q.
P – Q means that P is the sister of Q.

Let's check the options –
First option: B ÷ A + C
According to the given information, the family tree will be –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above diagram, A is the mother of C.
Second option: A – B ÷ C
According to the given information, the family tree will be –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above diagram, A is the paternal aunt of C.
Third option: A + B ÷ C
According to the given information, the family tree will be –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above diagram, A is the paternal grandmother of C.
Fourth option: A ÷ B + C
According to the given information, the family tree will be –

Here, the quadrilateral represents the male, and the circular figure represents the female in the figure. From the above diagram, A is the maternal grandfather of C.

Hence, the fourth option is correct.