Hemophilia Is Caused by an X-Linked Recessive Mutation in Humans

Multiple Choice

Hemophilia is caused by an X-linked recessive mutation in humans.If a woman whose paternal uncle (father's brother) was a hemophiliac marries a man whose brother is also a hemophiliac, what is the probability that their first child will have hemophilia? (Assume that no other cases of hemophilia and no hidden carriers exist in the pedigree. )

A) 0
B) 1/4
C) 1/2
D) 1/8
E) 1