A Patient, an African American, Is the Mother of a 9-Year-Old

A patient, an African American, is the mother of a 9-year-old child with sickle cell anemia. She asks the nurse if sickle cell anemia occurs frequently in her race. The correct response is that

A) it is a very rare disease.
B) approximately 1 of 500 African Americans has sickle cell anemia.
C) approximately 1 of 2,500 African Americans has the disease.
D) approximately 1 of 10 African Americans has the disease.