Answer:
A, pleiotropy.
Explanation:
Pleiotropy - genes that have multiple phenotypic effects. Remember that phenotype means a physical characteristic caused by a gene, such as eye color or fur patterns.
Incomplete dominance - when neither allele is dominant and they mix together in the phenotype. A popular example is a red flower crossing with a white flower and resulting in a pink flower.
Epistasis - when two genes contribute to the phenotype, but one gene completely masks another gene. An example would be labrador fur colors.
Multiple alleles - 3 or more alternative forms of a gene, but only 2 alleles can occupy an organism. An example is blood type.
Hope this helps!