The correct answer is B. The exodus of African-Americans from the rural south to the urban north
Step-by-step explanation:
The piece included in the question shows dozens of African-Americans that are walking to different places, this includes Chicago, New York, and St. Louis which are all cities in the North of the U.S. Based on this, it can be inferred, this painting was created to show "The exodus of African-Americans from the rural south to the urban north" that occurred during the 20th century and involved thousands of African Americans leaving the South and moving to the North because in there they could find jobs and there were not as many discriminatory laws as in the South. This is what is being shown in the piece because all people moving are African-Americans due to their skin color and all are leaving to go to cities in the North.