Chromosones and linked traits question?!?!?

males are XY and females are XX. colourblindness is recessive and is carried on the X chromosome. Because males only have one X, if they have (c) they are colourblind, they dont need 2 (c) alleles because they dont have a second X chromosome so the mutant X is always expressed. Females on the other hand have to be zygous for (c) in order to be colourblind. Those that only have one (c) have normal vision because the X chromosome without the mutation is expressed instead.