Hemophilia is an x-linked recessive disease. under which of the following conditions will a female child inherit hemophilia? both parents must have the hemophilia allele. only the father must have the hemophilia allele. both sets of grandparents must have the hemophilia allele. only the mother must have the hemophilia allele.

I believe the correct answer is the first option: Both parents must have the hemophilia allele.

Hemophilia is an X-linked recessive disease, which means that hemophilia is transmitted through the X sex chromosome. The female child gets an X chromosome from her mother and an X chromosome from her father. The X chromosome from her mother is dominant and If we suppose that mother has the gene for normal blood clotting and the X chromosome from her father has the gene for hemophilia, the female child won’t have hemophilia, but will be a carrier, which means that her children will have 50% chances of inheriting hemophilia. Since females have XX chromosomes, to have hemophilia manifested, both parents must have hemophilia.