What inheritance pattern results in a heterozygote phenotype that is intermediate between the two homozygotes?

The correct answer is based on the concept of incomplete dominance in genetics. Incomplete dominance occurs when the phenotype of a heterozygote is an intermediate expression between the phenotypes of the homozygous individuals. This means that instead of one allele completely dominating the other, both alleles contribute to the phenotype in a way that blends their characteristics.

For example, if one parent has red flowers and the other has white flowers, the offspring may have pink flowers, which is a mix of the two colors. This phenomenon highlights that neither allele fully masks the other, leading to a unique, intermediate phenotype in heterozygotes.

In contrast, complete dominance would result in the phenotype of the heterozygote being indistinguishable from the dominant homozygote. Codominance would lead to a situation where both alleles are fully expressed, as seen in blood types, where individuals can have one type A allele and one type B allele and express both traits simultaneously. Lastly, polygenic inheritance involves multiple genes contributing to a single trait, often resulting in a continuous range of phenotypes rather than distinct intermediate forms.