Final answer:
A female who has normal vision but is a carrier of the trait for red-green colorblindness would have the genotype XnX. The question's intended correct response is miswritten as option 2) XnXn, but it should be XnX, indicating none of the listed options are correct.
Step-by-step explanation:
Red-green colorblindness is a trait that is carried on the x chromosome. A female with normal vision who carries the trait for red-green colorblindness is represented by the genotype XnX, where 'X' represents the normal allele and 'Xn' represents the allele for colorblindness. Given the choices, option 2) XnXn is incorrectly written and should be XnX to represent the carrier female. Therefore, none of the provided options is correct, but the intended correct answer likely aimed to be option 2) XnX. As red-green colorblindness is a sex-linked, recessive trait, a female must have two copies of the colorblind allele to be affected. Since females have two X chromosomes, they can carry one normal allele and one colorblind allele, resulting in normal vision while still being carriers of the trait. They can pass on the colorblind allele to their offspring, with their sons having a 50% chance of being colorblind if the father has normal vision.