What was sold into enslavement after a local or tribal war?

Slavery among Native Americans in the United States includes slavery by Native Americans as well as slavery of Native Americans roughly within the present-day United States. Tribal territories and the slave trade ranged over present-day borders. Some Native American tribes held war captives as slaves prior to and during European colonization, some Native Americans were captured and sold by others into slavery to Europeans, and a small number of tribes, in the late eighteenth and nineteenth centuries, adopted the practice of holding slaves as chattel property and held increasing numbers of African-American slaves.

The answer is option c.