In humans, the condition for normal blood clotting (H) dominates the condition for non clotting (hemophilia) (h). Both alleles are linked to the X chromosome. A male hemophiliac marries a woman who is a carrier for this condition. (In this respect, a carrier is a woman who has an allele for normal blood clotting and an allele for hemophilia.) If they have a son, what are the chances he will be normal for blood clotting