Red-green colour blindness is a sex-linked trait. Red-green colour blindness ( X rg ) is the inability to distinguish between red and green colours.

Red-green colour blindness is a sex-linked trait. Red-green colour blindness (Xrg) is the inability to distinguish between red and green colours. The Xrg allele is recessive to the normal X allele. 

A normal woman has a father who has red-green colour blindness. She had a child with a man who does not have red-green colour blindness. 

What is the probability they will have a son with red-green colour blindness?

Select one:

a. 0.50

b. 0.13

c. 0.25

d. 0