Checks and balance
Hope this helps =]
At Jackson's request, the United States Congress opened a debate on an Indian Removal Bill. ... The Indian Removal Act of 1830 implemented the federal government's policy towards the Indian populations, which called for moving Native American tribes living east of the Mississippi River to lands west of the river.
B would be the answer because they were mapping the Mississippi river.
These areas had really never been mapped out, and if they were then they were not accurate.