Answer:
Natural Selection & Fitness
Explanation:
Horses have evolved to run as fast as possible because they are prey animals.
The hooves give advantages to the predecessors to the modern horse rather than the foot-bearing horses.
Thus when somebody inevitably becomes a snack, the hoof bearing horses lived longer. <u>(Natural selection)</u>
Because they've lived longer, they've had more babies. <u>(Fitness)</u>
Their babies are more likely to pass on the genes they've inherited from their successful parents, and the population of hooved-horses begins to exceed the population of footed-horses.
In this circumstance, all the footed-horses are gone. The population has <u>evolved.</u>
Hope this helps <3
PS: here's a source! https://www.amnh.org/exhibitions/horse/the-evolution-of-horses/on-your-toes#:~:text=Hooves%20and%20long%20legs%20help,many%20horses%20retained%20three%20toes.