Why did the Abbasid dynasty fall?

This is when the Abbasid Empire starts to fall apart; heavy taxation, agrarian disorder, societal mishap, and revolts all play the Abbasid Empire into the hands of the Buyids, a Persian group that captures Baghdad, the capital, and controls the Abbasid for a few years. ... The invasion of the Mongols, who sack Baghdad.

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.

the answer is b just took the test