Patients with sickle cell anemia and b-thalassemia major may not show clinical symptoms until the patient is at least 6 months of age because of which of the following?  a. The mutations are acquired...

Patients with sickle cell anemia and b-thalassemia major may not show clinical symptoms until the patient is at least 6 months of age because of which of the following?

 a. The mutations are acquired after the child is born b. The mutations are activated by dietary and maternal factors c. The mutations may not manifest clinically at birth because the presence of hemoglobin F decreases d. The mutations lead to elevations in a genes that compensate for the decreased gene expression