Explanation
The observed phenotypic ratio of 15:1 in a hybridization experiment in a plant suggests that two genes control the trait.
In a monohybrid cross, the phenotypic ratio is 3:1, indicating that a single gene controls the trait. However, in a dihybrid cross, where two traits are being studied, the phenotypic ratio is 9:3:3:1, indicating that two genes are controlling the traits.
In this case, the phenotypic ratio of 15:1 suggests that two genes control the trait, which could be located on different chromosomes or on the same chromosome but far enough apart to undergo independent assortment during meiosis.
Option A is incorrect because if only one gene controlled the trait, the phenotypic ratio would be 3:1, not 15:1.
Option C is incorrect because a phenotypic ratio of 27:9:9:9:3:3:3:1 would suggest that three genes control the trait.
Option D is incorrect because polygenes are a group of genes that control a single trait and have additive effects. The phenotypic ratio for polygenic inheritance is continuous and not a discrete ratio like 15:1.
