Answer:
Potential father 2
The child has one "I^B" allele. The potential father 2 carries "I^B" allele which is absent in the potential father 1.
Step-by-step explanation:
ABO blood group in human beings is regulated by three alleles. I^A and I^B alleles are codominant over each other and are dominant to the allele "i". The genotype of the mother with blood type "O" is "ii" while that of the baby is "I^Bi". The baby would have received the allele "i" from the mother and the allele "I^B" from the father.
The genotype of the potential father 1 can be "I^AI^A" or "I^Ai" while the genotype of the potential father 2 is "I^AI^B". Since the potential father 1 does not carry allele "I^B", he cannot be the father of the child. On the other hand, the potential father 2 carries one "I^B" allele and therefore, is most likely to have a child with blood type "B" if the mother has the blood type "O"