Two Parents Who Do Not Have Sickle Cell Anemia Have

Multiple Choice

Two parents who do not have sickle cell anemia have a child that has the disease.The parents are both:

A) homozygous for the sickle cell allele.
B) heterozygous for the sickle cell allele.
C) homozygous for the normal allele.
D) epistatic for the sickle cell allele.
E) pleiotropic for the sickle cell allele.