How Did the Mongols Use Conquest to Improve Their Empire

How did the Mongols use conquest to improve their empire?

A) To further the Mongol social system, they imposed their traditional tribal groupings on subjugated peoples.
B) They treated all subjugated men as slaves who were used as soldiers and agricultural workers.
C) They improved their own capital city by importing skilled workers from conquered regions.
D) They often exploited the labor of women of conquered territories who were forced to work at Mongol military camps.