In Poultry, the Genes for Rose Comb (R) and Pea

In poultry, the genes for rose comb (R) and pea comb (P) produce walnut whenever they occur together (R__ P__); single-combed individuals have the homozygous condition for both genes (rr pp).
(a)
Give the F₁ and F₂ phenotypic results of a cross of a pure-breeding rose comb (RR pp) with a pure-breeding pea comb (rr PP).
(b)
Give the phenotypic results of a cross of Rr Pp * rr Pp.
(c)
Give the phenotypic results of a cross of RR Pp * rr Pp.
(d)
Give the phenotypic results of a cross of Rr pp * rr Pp.
(e)
Give the phenotypic results of a cross of Rr Pp * rr pp.