Which of the following characteristics represent 'inheritance of blood groups' in humans?(i) Dominance (ii) Co-dominance(iii) Multiple allele (iv) Incomplete dominance(v) Polygenic inheritance

Blood groups A (IAi) and B (IBi) represents dominant-recessive relationship.Blood group AB (IAIB) represents co-dominance.Blood groups in humans is controlled by gene (I) which has three alleles (IA,IB and i) and therefore it is an example of multiple alleles.