Answer:
A. the government was forcing Indians onto reservations.
Explanation:
Before the Battle of Little Big Horn, George Custer, the commander of the United States troops against the Great Plain Indians, was given the order to send all the Indians (particularly Cheyenne and Sioux ) in that region to reservations area around 1876.
However, many of these Indians refused to move, as a result, a war ensued between the US government and the Indians.
Hence, it can be concluded that Battles like this were fought because "the government was forcing Indians onto reservations"