The correct response is: 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 mutations in genes located on the X chromosome.
- Males (XY) have only one X chromosome, so if they inherit the allele for hemophilia from their mother (who has two X chromosomes), they will express the disease.
- Females (XX) have two X chromosomes and typically need to inherit two copies of the hemophilia allele (one from each parent) in order to be affected, which is why they are affected less frequently than males. This pattern of inheritance is characteristic of X-linked recessive disorders.