Three strains of green-seeded lentil plants appear to have the same phenotype. The strains are designated G₁, G₂, and G₃. Each green-seeded strain is crossed to a pure-breeding yellow-seeded strain designated Y. The F₁ of each cross are yellow; however, self-fertilization of F₁ plants produces F₂ with different proportions of yellow- and green-seeded plants as shown below.

For what number of genes are variable alleles segregating in the G₁ x Y cross? The G₂ x Y cross? In the G₃ x Y cross? Explain your rationale for each answer.