How did the Song improve upon the Tang version of the civil service system? They mandated that most officials came from the military.
They made the examinations easier to pass.
They opened up the system to more people.
They required students to earn their degrees in three years.

Either C to D I'm not fully sure, I'd say C though

It's C : They opened up the system to more people.

disequilibrium means that either supply is greater than the demand for an available good, or that the demand for a product outstrips the available supply. it implies that the price for a is either too low creating large demand, or too high creating a large surplus of supply.

in 1803 the louisiana purchase took place, doubling the size of the country. by 1840 almost 7 million americans had migrated westward in hopes of securing land and being prosperous. the belief that settlers were destined to expand to the west is often referred to as manifest destiny.

explanation: