WILL GIVE BRAINLIEST, NEED HELP ASAP

Based on the section "A country full of mountains," how did deserts and mountains affect Chinese civilization?

A
They attracted people from around the world who wanted to hike and ski.
B
They became oases where large populations created huge farming settlements.
C
They created barriers that forced the people to focus on improving what they had.
D
They formed rivers and worked as boundaries to keep them from overflowing.