Final answer:
In human blood types, the presence of both A and B alleles leading to AB blood type demonstrates Codominance, where both alleles are equally expressed, unlike incomplete dominance.
Step-by-step explanation:
In human blood types, a person who inherits both the A allele (IA) and the B allele (IB) will have type AB blood. In this case, the A and B alleles show Codominance, because both alleles are expressed equally in the phenotype of the person. The surface antigens A and B are both present on the red blood cells, and neither one is dominant over the other. This differs from incomplete dominance, where a blend of traits would be exhibited. In the ABO blood group system, the type O allele (i) is recessive and does not produce any surface antigens on red blood cells. Therefore, the correct answer to the question is A) Codominance.