The graph shows changing population statistics during the early part of the twentieth century. A line graph titled African American population by region, 1900 to 1930 shows years on the x axis and population numbers on the y axis. The line labeled midwest starts at 500,000 in 1900, to 600,000 in 1910, to 750,000 in 1920, to 1,250,000 in 1930. The line labeled northeast starts at 400,000 in 1900, to 500,000 in 1910, to 700,000 in 1920, to 1,200,000 in 1930.

Which statement best explains what caused this population shift?
A. African Americans moved from rural areas in the South to cities in the Midwest and the North.
B. African Americans left factories in the South to find work on farms in the Midwest and the North.
C. African Americans moved from cities in the Midwest and the North to rural areas in the South.
D. African Americans left factories in the Midwest and the North to find work on farms in the South