Which of the Following Was an Environmental Factor Involved in the Tang's

Which of the following was an environmental factor involved in the Tang's overthrow of the Sui?

A) Drought led to a revolt of the peasants and the Tang took control during the disorder.
B) The Yellow River changed course and the extensive flooding led to revolts as the population faced starvation, allowing the Tang to seize power from the Sui.
C) Infertile soil caused by blowing loess led to starvation among the peasants, who then revolted against the Sui.
D) The Tang dammed the major rivers, forcing the starving population to change loyalties from the Sui.