What are the genotypes of the parents producing a 3:1 phenotypic ratio in the F1 progeny?

A 3:1 phenotypic ratio in the F1 generation typically occurs when both parents are heterozygous for a single trait, which means that they can produce gametes that carry both dominant and recessive alleles. This ratio is often seen in single-gene traits that follow Mendelian inheritance patterns, particularly when one trait is completely dominant over the other.

In the context of the answer, the chosen combination of genotypes provides the necessary conditions to generate such a ratio. When one parent is homozygous recessive (cc) for one trait and heterozygous (Pp) for another, while the other parent is also homozygous recessive for the first trait (cc) and has a heterozygous genotype (Pp) for the second trait, the offspring will indeed show the expected 3:1 phenotypic ratio for the dominant versus recessive expression of that single trait being analyzed.

For example, if we analyze a trait where "C" represents a dominant phenotype and "c" a recessive one (with "P" and "p" representing another trait), the parents (ccPp and Ccpp) will generate a mixture of Cc and cc offspring, with the "