Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group respectively. What would be the genotype of both mother and father?

a. Mother is homozygous for ‘A’ blood group and father is heterozygous for ‘B

b. Mother is heterozygous for ‘A’ blood group and father is homozygous for ‘B’

c. Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively

d. Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively