The correct answers are A) Hunter-gatherers used fire to burn plants and trees and D) Hunter-gatherers contributed to the extinction of some animals through overhunting.
The way in that hunter-gatherers altered the natural environment was the following: "Hunter-gatherers used fire to burn plants and trees and Hunter-gatherers contributed to the extinction of some animals through overhunting."
Hunter-gatherers were nomad people who followed the herds to hunt them. Until humans learned to developed agriculture techniques, they could settle in one place to grow crops. They used pointed tools for cutting that made of different materials, and they shaped these tools for different purposes.