Answer:
C. IBIB
D. IBiO
Explanation:
The blood group system comprises of three different kind of alleles, iA, iB, IO. As we know that a person gets two alleles for both traits, one from father and one from mother, and based on that a person gets its blood group. IA and IB are dominant to IO.
So, if a person has genotype IAIO he will have blood group A and if he has genotype IOIB he will have blood group B because A or B are dominant to O.
However, if a person has blood group O it means that he has genotype IOIO.
So, in this diagram we see that Eric has blood type O, which means that his genotype will be IOIO.
The Eric's mother Melissa has blood group B, which means that she can either had genotype IOIB and IBIB respectively.
Similarly, Eric's grandmother Tricia has genotype B which means that she can have genotype both IOIB and IBIB respectively.
Therefore, both C and D are correct options.