During the qing dynasty, irrigation and fertilizer use increased. this caused

a) increased trade with other countries

b) chaos (trouble/disorder) on the farms

c) more cities to grow

d) increase in population growth

During the Qing dynasty, irrigation and fertilizer use increased. This caused increase in population explosion.

Option  D

Explanation:

Last imperial dynasty of China “Qing/Ching Dynasty” ruled from 1644-1911 whose predecessors were Ming Dynasty Rulers, who lost their kingdom due to hyperinflation due to high trade  with Europeans by 16th century, which ultimately resulted in hunger, scarcity, crop failures, death from pending dues etc.

Hence, Qing Dynasty learned from predecessors and focused effectively on self development and reformation of sites for their safe life rather than more trading. They increased irrigation & fertilizers use for crops like rice, sweet potatoes, corn.

This excessive blasted with population explosion during 1650-1900 from nearly 100 to 500 million. Downfall of this last Chinese dynasty in 1911-1912 was due to external forces like western technologies interference, gross miscalculations and others.