I think the answer is "C" I believe
The state of Oklahoma had many reservations back then. Therefore, I believe that in<span> the late 1800s, the federal government attempted to place all plains Indians on reservations, most of which were located in the state of Oklahoma.
During this period, the main ancestors of the US were forcibly moved to reservations. This made their territory restricted severely compared to the time when they were free to move anywhere. </span>
