A woman suffers from colour blindness and her husband does not. They have a son and a daughter. Which one of the following statements is most probably correct?

The correct option is D

Son suffers from colour blindness while the daughter does not suffer from it

Colour blindness is hereditary disorder which can be transferred from parents to children. It is a recessive X linked mutation. If a woman inherits a normal X chromosome in addition to the one which carries the mutation, she will not express the mutation. Males only have one X chromosome, they have no spare normal chromosome to override the chromosome which carries the mutation. So, a male with the defective allele will express the disease too.

If a mother is suffering from Red/green colour blindness, then she is homozygous, i.e. both the X chromosomes carry the defective gene. So, when she passes on the X chromosomes to children, they get a defective copy of that gene. Thus, the son becomes colour blind as he has only one defective X chromosome and daughter becomes carrier as she gets a good copy of X chromosome from the father.