challenge: What is the main theme of the film 'Columbus on Trial' directed by Lourdes Portillo?
  
  A. The celebration of the 500th anniversary of Columbus's discovery
  B. The portrayal of Columbus as a hero who improved the lives of the native people
  C. A simulated trial that questions Columbus's motives and impact on the native population
  D. Columbus's journey to the New World and his discovery of new lands
  Answer: 