A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind

Options

A. 0.5
B. 1
C. Nil
D. 0.25

Answer

D

Explanation

Here it is not specified whether grandsons are through daughter or son and thus we have to consider all the grandsons i.e., both through the son and the daughter. In such a case the answer comes out to be one out of four (0.25).
If we consider the grandsons only through the son then the answer will be Nil.
If we consider the grandsons only through the daughetr then the answer will be 0.5.