The answer is C.
The man’s genotype must be AB. The woman’s genotype can be either BB or BO as both correspond to a blood type (which is a phenotype) of B.
Each parent passes on one allele. The man can contribute A or B and the woman can contribute B or O.
The possible genotype combinations are therefore AB, AO, BB, and BO. These correspond to the phenotypes AB, A, B, and B.
