$H{b}^A$ and $H{b}^S$ alleles of normal and sickle celled RBC are

The correct option is C Codominant alleles

The parental alleles, both are expressed in the F₁ progeny are called co-dominant alleles and the process is called Co-dominance. In human beings the parental alleles Hb^A Hb^S are present in the form of a pair in the progeny, sickle cell anemia appears in the progeny.

So, the correct option is ‘Codominant alleles’