What describes a trait where the phenotype of a hybrid displays a blending of the two alleles?

The scenario described involves a hybrid organism where the phenotype reflects a blending of the two alleles, which is characteristic of incomplete dominance. In this type of genetic interaction, neither allele is completely dominant over the other, resulting in an intermediate phenotype.

For example, if one parent contributes a red allele and the other a white allele, the offspring may exhibit a pink phenotype, which is a blend of the two. This stands in contrast to complete dominance, where one allele completely masks the effect of the other, leading to a phenotype that only shows the dominant allele.

Codominance, on the other hand, would manifest as both alleles being expressed distinctly without blending, such as in AB blood type where both A and B antigens are present. Multiple alleles refer to the existence of more than two alleles for a genetic trait within a population but does not pertain to how these alleles interact in terms of dominance or expression in a hybrid individual. Thus, the correct association with the blending phenotype is indeed incomplete dominance.