In poultry, two genes R and P, control the shape of the comb on the head. The following genotype/phenotype relationship applies to the two genes and the phenotype: R- P- animals have a 'walnut' comb, R- pp animals have a 'rose' comb, rr P- animals have a 'pea' comb, and rr pp animals have a 'single' comb. What will the comb phenotypes be for the progeny of the cross RR Pp x rr Pp