Answer:
evolution, genetic mutation and selection
Step-by-step explanation:
The earliest progenitors of horses had fingers, while their contemporary counterparts have hooves on their limbs. The presence of horse hooves could be caused by a variety of factors.
These changes might result from genetic mutations that altered the shape of the digits in the affected limb. A sudden alteration in DNA can lead to a mutation, and such a mutation can subsequently change a horse's phenotype.
It is possible that the horse's characteristics were altered over time through evolution.
The variation in the phenotype of the horse's limb digits may also be due to natural selection.