Which of the following characteristics represents 'Inheritance of blood groups' in humans?
I. Dominance
II. Codominance
III. Multiple allele
IV. Incomplete dominance
V. Polygenic inheritance

Dominance, codominance and multiple alleles are the characteristics that represent 'inheritance of blood groups' in humans. ABO blood groups are determined by the gene I.
There are multiple (three) alleles; I^A, I^B and i of this gene. Allele I^A and I^B are dominant over i. However, when l^A and I^B alleles are present together, they show codominance.