Genes for colour blindness in humans are carried by

The correct option is A Both
Color perception defect is due to a mutation on the X-chromosome (i.e. a red-green color blind allele). X-linked red-color blindness is a recessive trait.

Since, it is a X-linked trait, genes for colour blindness can be carried by both Mother and Father. Since males have only one X-chromosome, if this chromosome has the red-green color blind allele, the males will have the color perception defect. Females have 2 X-chromosomes. Both X-chromosomes must carry the mutant allele for the females to be color blind. Red-green color blind females are homozygous for the recessive allele. Females with one mutant allele and one normal allele are heterozygous "carriers". They are not color blind, but they can pass the color blindness to their children

So, the correct answer is 'Both'.