Question

what is the best evidence to prove that irene was heterozygous for hemophilia?
○ elizabeth is not a carrier for the trait.
○ tatiana carried the recessive allele.
○ her brother has hemophilia and her sister is a carrier.
○ two of her sons have hemophilia and one does not.

Explanation:

Hemophilia is X - linked recessive. A heterozygous (carrier) female has a 50% chance of passing the allele. Irene’s two sons with hemophilia (got the allele from her) and one without (got the normal allele) show she’s heterozygous. Other options don’t directly prove her genotype.

Answer:

D. Two of her sons have hemophilia and one does not.