To determine the possible blood types of the offspring you have to create a Punnet square crossing the genotypes of the parents.
The male parent has a blood type A, his genotype is AO, which means that his gametes can carry the alleles "A" or "O"
The female parent has a blood type B, his genotype is BO, which means that her gametes can carry the alleles "B" or "O"
Cross the alleles of the parents to determine the possible genotypes of their offspring:
The genotypes of the offspring and their phenotypes are:
AB → Blood type AB
AO → Blood type A
BO → Blood type B
OO → Blood type O
All of the given options are possible blood types of the offspring so the correct answer is All of these.
