Final answer:
During WWI, the African-American population in the southern United States witnessed significant changes through the Great Migration, which saw increased participation in northern economies and politics, despite continued segregation in the military and at home. Post-war, these experiences contributed to the strengthening of the civil rights movement, despite an expectation to revert to pre-war social orders. Therefore correct option is D
Step-by-step explanation:
During World War I, the African-American population of the southern United States experienced significant changes. Many African Americans moved to Northern cities during what is known as the Great Migration, seeking work in factories that had been vacated by men who went to war. This demographic shift saw African Americans voting more freely, participating in politics, and finding employment beyond traditional roles and sectors. However, military service for African Americans continued to be segregated, with African American soldiers serving in all-Black units and facing discrimination within the armed forces and at home.
Post-war, the impact of these experiences and wartime contributions led to a strengthening of the civil rights movement, although immediate changes were limited and the struggle against discriminatory practices continued. The war brought about temporary economic opportunities, but after the conclusion of the war, there was a cultural expectation for a return to the previous social order, which included disenfranchisement and segregation under Jim Crow laws. Nonetheless, the mobility and the prospect of better lives ignited by the war led to ongoing migration and a sustained push for greater equality.