Three alleles, A, B, and O, govern human blood typing. Alleles A and B are codominant with each other, and both are dominant to type O. A second gene affecting blood type is Rh-factor, which gives the blood a plus (+) or a minus (-). The Rh+ allele is dominant to the Rh- allele. What would be an expected phenotype of a cross between a woman who has AB blood and is Rh+ to a man who has O blood and is Rh-? A. The offspring could be B-
B. The offspring could be A+
C. The offspring could be O-
D. The offspring could be AB+