The three statements that best describe prehistoric hunter-gatherers are:
- They discovered how to use fire.
- They formed groups for protection.
- They farmed and raised livestock. (This statement is not correct as hunter-gatherers did not farm or raise livestock; this is characteristic of later agricultural societies.)
Therefore, the correct answers are:
- They discovered how to use fire.
- They formed groups for protection.
Note: The third choice excluding the inaccurate statement (farming and raising livestock, and settling in walled villages) does not apply to hunter-gatherers. They were generally nomadic and did not engage in these practices until the advent of settled agricultural societies.