The right answer is c. Native Americans lost land during the Revolution.
During the American Revolution, both sides, British and Americans, persuaded Indian tribes to help them out during the conflict. The result was the disintegration of the 6 tribes that made up the Iroquois League, as the Indians took different sides in the battle. Many whites used this excuse to destroy Indians villages, Indian populations and take control of their lands. By the end of the conflict, the new American government did not cooperate with the asking of the indigenous and later on contributed to conquer their lands and decimate its population.