A women with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy

Options

A. must have normal colour vision
B. will be partially colour blind since he is heterozygous for the colour blind mutant allele
C. must be colour blind
D. may be colour blind or may be of normal vision

Answer

D

Explanation

A woman, whose father was colour blind, will be carrier for colour blind trait. Marriage of this woman with a colour blind man will result into following possibilities.