Which of the following was a cause of the great migration?
• expansion of cotton fields
• world war i
• civil rights movement
• the 19th amendment
• plessey v. ferguson

I believe the answer is: world War I

Following the world war I, the southern states experienced economic crisis which lead to massive unemployment in southern states. Because of this, around 6 million people decided to migrate to northern states in order to obtain low paying jobs on those states.