Another blood disease, hemophilia, is caused by the failure of blood to clot. The genetic basis for the disease is due to one of two dysfunctional clotting factor genes, recessive alleles that lead to the disorders hemophilia A and hemophilia B. Due to the long history of arranged European royal marriages within a relatively small sample population, the prevalence of both hemophilia and G6PD-deficiency disorder are both high. In fact, in certain family lines sons, but not daughters, are nearly always either born with both G6PD-deficiency and hemophilia A-disease or are born completely healthy. In other family lines sons, but not daughters, are born about a quarter of the time with both G6PD-deficiency and hemophilia B.
(G = G6PD gene, A = Hemophilia A, and B = Hemophilia B, X = X chromosome, Y = Y chromosome)
Which of the following arrangement of loci on chromosomes best explains these observations?
A
B
C
D
or
E
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