Refer to the Diagram Below Showing a Pedigree of a Sex-Linked

Multiple Choice

Refer to the diagram below showing a pedigree of a sex-linked recessive trait. In generation II, female number 5 marries a man and has three children. One daughter and one son do not have the recessive trait; the other son does have the recessive trait. Based on these results, one can conclude that

A) the mother is heterozygous for the trait.
B) the mother is homozygous for the trait.
C) a mutation has occurred.
D) the father is heterozygous for the trait.
E) the father is homozygous for the trait.