Final answer:
The probability that Jane's first child will be a son who can see color is 25%. This calculation combines the 50% chance of having a male child and the 50% chance that he will inherit normal vision, given the X-linked recessive inheritance of colorblindness. The correct answer is option a.
Step-by-step explanation:
The probability that Jane's first child will be a son who can see color needs to be calculated considering the inheritance pattern of colorblindness and the sex of the child. Since colorblindness is an X-linked recessive trait, a son can only be colorblind if he inherits the recessive allele from his mother, because males have only one X chromosome (XY) and females have two (XX).
Jane's father is colorblind, which means Jane must carry one allele for colorblindness. For Jane's son to be colorblind, he would need to inherit this recessive allele. However, because her husband has normal vision, he provides a normal X chromosome. The son's probability of being colorblind is therefore 50%. Now, to find the probability that Jane has a son who can see color, we need to consider the probability of having a son in the first place, which is 50% (half the children will be male, and half will be female).
The final probability is the product of the probability of having a son (50%) and the probability that the son is not colorblind (also 50%), which is 0.5 * 0.5 = 0.25, or 25%. Therefore, the correct option in the final answer is A. 25%.