to become better hunters. in order to re-populate the Earth. in response to an altering environment. to become useful for humans.
I gave my students this multiple choice question: According to the fossil record, the first horses were smaller than modern species. Throughout time, horses have gradually changed

Only one answer is correct among these 4 choices:
- to become better hunters.
- in order to re-populate the Earth.
- in response to an altering environment.
- to become useful for humans.

Could you tell me which one is correct?

in response to an altering environment.