The main means of subsistences for the native americans that lived on the great plains was hunting antelope and

The other animal Native Americans depended on for survival was the buffalo. This big animal, one out of a few surviving animals that once belonged to a  group of animals known as megaphauna (literally, huge animals) was essential fr Native Americans who used nearly all the parts of the animal for different purposes. The flesh and most body organs was used as food; the bones were used to build utensils and the internal framework of their tepees (portable tents), and the skins were used for clothing and as outer cover of their tepees.

In the nineteenth century, after the shameful defeat of General Custer and his 7th Regiment of Cavalry resulting in a massacre in the hands of a group of many different Native American tribes, the U.S. government decided to defeat the Native Americans (unbeatable using military force alone) by starving them, so the unrestricted hunting of buffalo was encouraged by the government which had the effect of nearly killing off all the buffaloes in America (a clear example of ecocide; complete destruction of a part of an ecosystem), changing the ecosystems of the plains forever and forcing Native American tribes to surrender and get imprisoned in reservations.

hello, your actual correct answer is c. taxes.

factories are actually the second biggest but on your optian list its taxes.