In shorthorn cattle, the genotype RR causes a red coat, the genotype rr causes a white coat, and the genotype Rr causes a roan coat. A breeder has red, white, and roan cows and bulls. What phenotypes might be expected from the following matings and in what proportions?
(a) Red × red
(b) Red × roan
(c) Red × white
(d) Roan × roan.