What was the main reason behind the first wave of the Great Migration during World War I, prompting African Americans to leave t
he South? A.) the rise of the Ku Klux Klan, which only existed in southern states
B.) the appeal of sharecropping, where they could work the land but not own it
C.) a booming increase in oil production and refinement in Oklahoma
D.) a need for factory workers in large cities to help produce machinery and supplies
