A father has blood group A and mother has blood group B ,What will be the possible blood group of the progeny ?

A, B, AB, and O.

Due to codominance of "I^A" and "I^B” alleles, the genotype "I^AI^B" produce “AB” blood group respectively. Thus, the six genotypes give total four phenotypes. Hence, parents with A and B blood group can have child with A, B, AB and O blood groups.