Answer:
Codominance
Explanation:
This is when 2 or more alleles are expressed at the same time. In other words they both affect the phenotype. In the example of human blood ABO type we have an allele for A = IA, B= Ib O=i
IAIb = AB blood type
IbIb = B blood type
Iai = A
IaIa = A bloody type
Ibi = B blood type
ii = O blood type