The following passage (paragraph 4) mainly shows that .
The Great Migration is a term that refers to the movement of African Americans from the South to large cities in the North between approximately 1916 to 1940 in its first wave. World War I cut off the flow of European immigrants to the United States. Northern factories were growing and needed more workers. They recruited African Americans from the South to help make up for the shortage of workers. African Americans were eager to leave the South because of Jim Crow laws that led to mistreatment and violence against them. Many were sharecroppers who had difficulty surviving economically, especially when an insect infestation decimated the cotton crop during the war. Harlem also attracted black immigrants from the Caribbean, promising greater prosperity and economic opportunity.
Answer choices for the above question
A. during the war, many African Americans also moved from America to the nations of the Caribbean
B. the war caused work shortages that were filled by African Americans in a pattern of migration from the South that became known as The Great Migration
C. the strains of war caused the government to institute a mandatory migration of African Americans from their Southern homes to new jobs in Northern factories
D. since the Civil War, African Americans had been looking for an opportunity to exit the oppressive government of the Southern states