A woman with blood group A can have either of the genotypes −IAI0. or IAIA. A man with a blood group B can have either of the genotypes −IBI0 or IBIB. Since the given question doesn't mention the specific genotype, thus any of the above-mentioned genotypes can be crossed. As a result of which there is a maximum possibility of obtaining all the blood groups (A,B,AB,0) among their progeny.