Question

if an individual allele has more than one effect on the phenotype, this is called
multiple choice
polygenic inheritance.
epistasis.
blending inheritance.
multiple alleles.
pleiotropy.

Explanation:

The question describes a single allele affecting multiple phenotypes, which is the definition of pleiotropy. Polygenic inheritance involves multiple genes affecting one trait; epistasis is gene interaction; blending inheritance is outdated (traits mix); multiple alleles are multiple variants of a gene.

Answer:

pleiotropy