Even Though It Is Deadly, the Huntington's Disease Allele Can

Even though it is deadly, the Huntington's disease allele can remain in the population, because

A) the dominant allele sometimes reverts to a recessive form.
B) it is sex-linked to the male gamete, and females do not carry the allele.
C) people with the disorder often live long enough to reproduce.
D) it is autosomal and can be masked by a codominant harmless allele.