What was the great migration during world war 1?

The Great Migration on the US home front during World War I involved a. African Americans moving south from the North to work in factories Between 300,000 and 500,000 African Americans left the South during World War I to settle in Northern cities which became known as the "Great Migration". Between 750,000 and one million left the South in the 1920s.

the social contract theory

the answer is b for brother