Final answer:
The purpose of the Black Hills Gold Rush in 1875 was to search for valuable minerals and gold. This rush for gold in the Black Hills was a significant event in the western expansion of the United States.
Step-by-step explanation:
The purpose of the Black Hills Gold Rush in 1875 was to search for valuable minerals and gold (c).
With the discovery of gold in the Black Hills, thousands of prospectors illegally began mining in the area, which was newly granted Sioux lands. The government attempted to negotiate with the Native American tribes to lease or buy the land, but when they refused, the government imposed a price for the land and forced the tribes to move. This rush for gold in the Black Hills was a significant event in the western expansion of the United States.