Question

why is the yellow river (huang he river) sometimes referred to as \chinas sorrow\ in chinese history?
the sporadic flooding of the river has killed millions of people over the course of chinese history dating back to 1500 bce.
it is the final resting place of the last emperor of the shang dynasty.
the yellow river has served as the physical and political border between china and the mongols up until 1200 ce.
the river water is polluted due to ancient chinese cultural practices and therefore could not be used for farming or clean drinking water.

Explanation:

The Yellow River has been notorious for its sporadic and often - devastating floods throughout Chinese history, resulting in the loss of millions of lives. This is the main reason for it being called "China's Sorrow". The other options are not the main reasons for this moniker.

Answer:

The sporadic flooding of the river has killed millions of people over the course of Chinese history dating back to 1500 BCE.