Sickle-cell anemia is an example of codominance. what implications does this have for people with one or two copies of the sickle-cell gene?

a. people with two copies of the mutated gene have healthy red blood cells. people with one copy of the mutated gene don't have the disease but are carriers of the disease.
b. people with two copies of the mutated gene have sickle-cell anemia. people with one copy of the mutated gene have both healthy and misshapen red blood cells and are carriers of the disease.
c. people with two copies of the mutated gene are carriers of the disease. people with one copy of the mutated gene don't have the disease.
d. people with two copies of the mutated gene have sickle-cell anemia. people with one copy of the mutated gene have healthy red blood cells.