C. X-linked recessive because all males with the allele have hemophilia, and only some females if they receive two recessive alleles.
Explanation: Hemophilia is caused by a recessive allele located on the X chromosome. Males have only one X chromosome (XY), so if they inherit the recessive allele, they will express the disorder. Females have two X chromosomes (XX), and for them to be affected, they must inherit two copies of the recessive allele (one from each parent). This is why only some females (25% in this case) are affected if they are carriers of the recessive allele.