Why were early people in north america able to build complex cultures?
a.
they had learned how to farm.
b.
they had learned how to start fires.
c.
they had advanced weapons.
d.
they had a written language.

A. They learned how to farm
This means they no longer have to be hunters and gatherers and follow their food by the seasons. They can now stay in one place and worry less about their food sources and focus on other things to make a better civilization.

Not sure this is a hard one huh