Which words or phrases describe the central plateau? can me more then one answer.

altiplano central
area where most of the population lives
high, flat land surrounded by mountains
humid
pleasant climate
rio bravo
snow-covered mountains

The caste system in india was used for what purpose? a) to ensure that all people had an adequate income b) to prevent the rich from taking too much power c) to provide social control and conformity according to one’s birth d) to draft a military capable of defending india from mongol invasion