Apart from showing co- dominance , the ABO blood grouping also shows us what?

Multiple alleleism

The correct answer is option (2) -Multiple alleleism

 Apart from showing co-dominance, the ABO blood grouping also demonstrates multiple alleleism. Multiple alleleism refers to the presence of more than two alleles for a particular gene in a population. In the case of the ABO blood group system, there are three main alleles: IA, IB, and i, which determine the A, B, and O blood types, respectively.