Answer:Four phenotypes are possible in a flock of ducks that contains all the possible combinations of these three alleles.As in the ABO blood system 4 phenotypes are possible in this case.GenotypePhenotypeHH,Hi(H)II,Ii(I)HI(HI)ii(i) Solution Answer:Four phenotypes are possible in a flock of ducks that contains all the possible combinations of these three alleles.As in the ABO blood system 4 phenotypes are possible in this case.GenotypePhenotypeHH,Hi(H)II,Ii(I)HI(HI)ii(i).