What geographic feature provided the center of early human cultures in the south american continent?

Adesert is an example of a(n) and the gobi desert is an example of a(n) a. ecosystem biome b. biome ecosystem c. ecosystem climate d. climate biome

Does anyone know the answers for these

In which area will soil formation be greatest? a a steep slope in a warm, b wet climate a flat area in a warm, c wet climate a north-facing area on a steep slope a flat area in a cold, d wet climate description