Inheritance of the ABO blood groups is controlled by three alleles $I^{A}$, $I^{B}$ and $I^{O}$. What are the possible genotypes of a person with blood group A?
- A$I^{A}I^{A}$ only
- B$I^{A}I^{A}$ and $I^{A}I^{B}$ only
- C$I^{A}I^{A}$ and $I^{A}I^{O}$ only
- D$I^{A}I^{A}$, $I^{A}I^{O}$ and $I^{A}I^{B}$