The child must have a father who is colorblind and a mother who is a carrier/ is colorblind.
Explanation:
The genetic code for color blindness is carried upon the x chromosome. This means that a male- who has only one X chromosome- only needs their mother to be a carrier to be colorblind. Women on the other hand, need two to be color blind, as the faulty x chromosome can be weeded out by the other.
Therefore, the father, in order to pass on the colorblindness, must be colorblind himself, whereas the mother only needs to be a carrier (or can be completely color blind herself).
