What was the major course of migration to the cities at the turn of the century

Great Migration, in U.S. history, the widespread migration of African Americans in the 20th century from rural communities in the South to large cities in the North and West.

Explanation:

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 actually b.   as habitats are destroyed, animals and plants may become extinct.   , according to edge nuity