What is the expected phenotypic ratio in the offspring of a monohybrid cross?

In a monohybrid cross, which involves a single trait controlled by one gene with two alleles, the expected phenotypic ratio among the offspring is 3:1. This ratio arises when two heterozygous parents (for example, Tt x Tt) are crossed, where "T" represents the dominant allele and "t" represents the recessive allele.

During this cross, the offspring inherit alleles from both parents, producing four possible combinations: TT, Tt, Tt, and tt. The genotypes TT and Tt express the dominant phenotype, while tt expresses the recessive phenotype. Therefore, three of the four possible combinations yield the dominant phenotype (TT and Tt) and one combination yields the recessive phenotype (tt). This results in a phenotypic ratio of 3:1, demonstrating the dominance of the trait associated with the dominant allele.

The other options represent outcomes from different types of genetic crosses or inheritance patterns; for instance, a 1:2:1 ratio is typical of a monohybrid cross focused on genotypes, while a 9:3:3:1 ratio is characteristic of a dihybrid cross involving two traits, and a 1: