What caused the downfall of the han dystany?

N 184 CE, two major Daoist rebellions—the Yellow Turban Rebellion and the Five Pecks of Rice Rebellion—broke out. In order to fight these rebellions Emperor Ling gave military commanders control over their own provinces, but this gave way to a long power struggle. In 189 CE, Emperor Ling died and was succeeded by his 13 year old son, Liu Bian, known as Emperor Shao. Empress Dowager He was regent, and her older brother, General-in-Chief He Jin, became the most powerful official in the court. He Jin wanted to exterminate the Ten Attendants, a group of influential eunuch officials. He summoned General Dong Zhuo to march on the city. The plot was discovered by the eunuchs, and He Jin was killed. In response the Emperor ordered indiscriminate killing of the eunuchs. The survivors kidnapped the Emperor and fled, only to later commit suicide upon General Dong Zhuo's arrival. The General would then replace Emperor Shao with the Prince of Cheniliu, known as Emperor Xian. Xian would be the last emperor of the Han Dynasty.

Source: Boundless. “The Fall of the Han and the Three Kingdoms Period.” Boundless World History I: Ancient Civilizations-Enlightenment Boundless, 19 Nov. 2016. Retrieved 13 Mar. 2017 from https://www.boundless.com/world-history/textbooks/boundless-world-history-i-ancient-civilizations-en...

Ithink the answer is b, monopoly