What contributed to the downfall of the Han dynasty? Choose four correct answers.

The peasants were upset after the Yellow River flooded and resulted in a famine.
The peasants organized a rebellion against the government.
The people revolted against the harsh policies of the government.
The peasants united with nomadic invaders and killed the emperor’s son.
Rivalries developed between powerful families.
Emperors were not leaving behind heirs, or the heirs were too young to rule.