One Form of Hemophilia Is Caused by a Sex- Linked

One form of hemophilia is caused by a sex- linked recessive gene.Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia.What is the probability that their first son will have hemophilia?

A) 1/4
B) 1/16
C) 1/8
D) 3/4
E) 1/2