Which of the following statements best describes the process of how later paleo-indian cultures replaced earlier ones?

If your chocies are the following:
New groups of hunter-gatherers migrated from other areas and replaced the older groups.
Over time, groups adapted to changing conditions and developed new tools and habits.
Earlier cultures died out because they could not adapt to changes in the environment.
Ice Age animals such as mammoths migrated to other areas, forcing cultures to find different food sources.

Then the answer is Over time, groups adapted to changing conditions and developed new tools and habits.