Final answer:
Red-green color blindness is a sex-linked recessive trait in humans. The genotypes of the parents would be XBXb (mother) and XBY (father). The probability of having a color-blind child is 50%.
Step-by-step explanation:
Red-green color blindness is a sex-linked recessive trait, which means it is carried on the X chromosome. Since males have one X chromosome, if they inherit the colorblindness gene from their mother, they will be colorblind. Females, on the other hand, need to inherit two copies of the colorblindness gene, one from each parent, to be colorblind. In the given scenario, the parents are both carriers of the colorblindness gene, meaning they each have one normal copy of the gene and one colorblindness copy. Therefore, their genotypes would be XBXb (the mother) and XBY (the father).
The probability of having a color-blind child can be determined using a Punnett square. Since the mother and father are both carriers, the chance of passing on the colorblindness gene to each child is 50%. Therefore, the probability of having a color-blind child would be 50%.