Answer:
codominance
Step-by-step explanation:
Codominance is a situation where the alleles of a gene are active, that is, there is no dominance relationship between them, so the two alleles are expressed, as is the case with the horse shown in the question above.
Generally, in the formation of a phenotype, one allele stands out against the other (remember that every gene is formed by a pair of AA, Aa or aa alleles). For the father's eye color to be repeated in his son, for example, it is necessary that the gene that determines this characteristic has a dominant allele. The other allele of this gene in the child will be the recessive allele. It happens, in some cases, that the two alleles (recessive or dominant) have the same dominance relation over each other and there is a mixture of phenotypes of both. A beautiful example of this mixture is the birth of horse species with a spotted coat.