What was the primary reason for the increased migration of African Americans to cities during World War I?

Driven from their homes by unsatisfactory economic opportunities and harsh segregationist laws, many Black Americans headed north, where they took advantage of the need for industrial workers that arose during the First World War

Explanation:

Driven from their homes by unsatisfactory economic opportunities and harsh segregationist laws, many Black Americans headed north, where they took advantage of the need for industrial workers that arose during the First World War.

answer would be b, a tariffs main purpose is to protect domestic production and jobs.