Answer:
The possible phenotypes for the father are B negative or B positive.
Step-by-step explanation:
First, let's answer the ABO system.
The question informs us that the Mother is Type A and that she has a Type O daughter. This means that the Mother's genotype is A / O because the daughter must have at least one Type O allele inherited from the mother and one from the father.
The question also tells us that they have a son with a type B phenotype. We already know that one of the father's alleles is O, and necessarily the other allele must be B, so the father's genotype is B / O.
In relation to the Rh system, the couple's son is negative. Which means that he must inherit a recessive allele from his mother and one from his father. We know that the mother is Positive, so her genotype must be R / r. The father can be either Positive R / r or Negative r / r.
So the possible phenotypes for the father are B negative or B positive.