That was the 'movement' called Khmer rouge. The leader associated with it was pol pot.
Answer:
Troposphere
Explanation:Troposphere. Known as the lower atmosphere almost all weather occurs in this region. The troposphere begins at the Earth's surface and extends from 4 to 12 miles (6 to 20 km) high. The height of the troposphere varies from the equator to the poles.
I think that B) availability of cheap labor in India
The Roman government had a republic and some of there principles like electing a leader its still used in the American government today.