4) A child has type AB blood. His mother has type B blood. Which of the following genotype/phenotype combinations IS consistent with the biological father of this child? A) Type B, IBIB B) Type B, IBIo C) Type AB, IAIB D) Type O, IoIo E) None of the above are consistent with the phenotype of the child.

C) Type AB, IAIB

Explanation:

The ABO system for blood type has multiple alleles, where IA and IB are codominant and Io is recessive to both of them.

The genotypes and phenotypes for blood type are therefore:

If a child has type AB blood, and his mother has type B blood, the IA allele must have been inherited from its father. Therefore, the only consistent genotype for the father among the given options is IAIB.