Correct choice is (b) 50%
Best explanation: The percentage of children which are colour blind if their father is colour blind and the mother is a carrier for colour blindness is 50% because the father will produce Xc and Y chromosome and the mother will produce Xc and X chromosomes. Their children will have the genotypes- XcY, XY, XcXc and XcX. Therefore, 50% of children are colour blind, 25% have normal vision and 25% are the carriers of the disease.