Question

in the abo blood group system, what is/are the possible genotype(s) for a person who has blood type a?
○ aa and ao
○ oo
○ aa
○ ao

Explanation:

In the ABO blood group system, the A allele is dominant, and the O allele is recessive. A person with blood type A can have either two A alleles (genotype AA) or one A allele and one O allele (genotype AO), because the A allele will express the A blood type phenotype even when paired with O. The OO genotype is for blood type O, and having only AA or only AO is incomplete as both AA and AO can result in blood type A.

Answer:

A. AA and AO