The correct answer is the U.S. troops - on behalf of the U.S. government. The period between 1820 and 1860 saw the decline of the conditions of the Indians in American territory. Many were decimated, thousands of them were forced to leave their homes in the South and move west of the Mississippi Rivers (this is the so-called Trail of Tears), and many others were even slaved.
It's D. It's the only answer that makes sense. Slaves remained where they were; they weren't deported. They stayed under rule of the American Government. And B is just wrong.<span />
