Everything that is mentioned here applies. Still, two options that apply the most are They started to farm and
They raised livestock.
Explanation:
People started farming, because they realized that they need permanent settlements, and thus to have constant source of food. Even before this people were gathering food, and that hasn't changed for a long period of time. Of course, they also started domesticating animals, so they can produce their own food. Of course, some of them moved to other areas, so they could find new animals to hunt.
