Answer:
Codorminance.
Step-by-step explanation:
The type of inheritance pattern is codorminance because in codorminance the two alleles in the gene are expressed, no allele was able to masked the express on the other allele. The chestnut colored horse allele is expressed likewise the white
colored allele too is expressed none of the two alleles mask the Expression of the other, the two are expressed to give offsprings roan colored which is an indication of the two expression.