The correct option is D A, B, AB
Genotype of the parent having blood group A is AO
Genotype of the parent having AB blood group is AB.
P generation : AO x AB
Gametes : A O A B
F1 generation : AA AO AB BO
Phenotypes : (blood grp) (A) (AB) (B)
Thus, possible blood groups of children can be A, B or AB.