In sex-linked inheritance, how many functional copies of the colorblind gene are required for an individual to have normal red and green color vision?

Identify that the gene responsible for red and green color vision is located on the X chromosome. This means males have one copy of this gene, while females have two copies.

Consider that for normal red and green color vision, an individual needs at least one functional copy of the gene. In males, this means their single X chromosome must have a functional gene. In females, at least one of their two X chromosomes must have a functional gene.