For the first question regarding the map, the MOST accurate statement would likely be:
B Urban areas in the Midwest saw a boom in African American population.
The Great Migration resulted in significant migration of African Americans from the rural South to urban areas in the North and Midwest, particularly during the early 20th century.
For the second question regarding which played the biggest role in the population shift, the best answer would be:
C Jim Crow laws.
While World War I and World War II were important factors that contributed to migration, the oppressive conditions created by Jim Crow laws in the South were a primary motivating factor for many African Americans to seek better opportunities and living conditions in the North and Midwest.