Most cases of colorblindness result from abnormal recessive genes located on the X chromosome that ...

Most cases of colorblindness result from abnormal recessive genes located on the X chromosome that are not duplicated on the Y chromosome. Which of the following statements accurately predicts the outcome for the children of a father with typical genes and a mother with abnormal genes?
 
  a. Half of the couple's daughters, but none of their sons, are likely to be colorblind.
 b. Half of the couple's sons, but none of their daughters, are likely to be colorblind.
 c. None of the couple's children are likely to be colorblind.
 d. All of the couple's children are likely to be colorblind.