The "lost generation" is a term that is often used to describe

For celebrities or famous people who didn't believe in the U.s.'s economic system so this kind of group is called the lost generation.

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.