Answer in one wo
1. A change in the surroundings that makes us to react to it.

You don’t list any options but the one that frets overspending and the consequences of that.

The correct answer is a. when they started making tools that will them in cultivating lands, they could raise crops and that made them attached to one place for a longer period of time. after that, they started domesticating animals and building their own permanent settlements that resemble the ones we have today.