challenge: What is the main subject of the book 'Hammer and Hoe: Alabama Communists during the Great Depression'?
  
  A. The history of the Great Depression in the United States
  B. The rise of communism in the Southern United States
  C. The life of Robin D. G. Kelley
  D. The labor, racial, and social history in Alabama during the Great Depression, focusing on black communist organizing
  Answer: 