Answer :
The correct answer is C. sell their unoccupied territory. The one from 1885 allowed them to sell the land that they didn't need, which in turn meant that the land was considered to belong to individual persons who would sell them and not the whole tribe. This was an easy way for the United States to take this land because you could always find a single person who would take the deal.
The answer for this question is C. sell their unoccupied territory.