Comb shape in chickens represents one of the classic examples of gene interaction. Two gene pairs interact to influence the shape of the comb. The genes for rose comb (R) and pea comb (P) together produce walnut comb. The fully homozygous recessive condition (rrpp) produces the single comb. Assume that a pea-comb chicken is corssed with a walnut-comb chicken and the following offspring are produced: 30 walnut, 15 rose, 9 pea and 2 single.
What are the probable genotypes of the parents
Select one of the following: