The choices can be found elsewhere and as follows:
codominance
complete dominance with the IA allele being dominant
incomplete dominance
complete dominance with the IB allele being dominant
I think the correct answer is the first option. The ia and ib alleles of the abo blood group gene i exhibit codominance. It is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent.
