The answer to the question is D.
Rail connections to the Great Plains proved especially devastating. After acquiring horses, Indians there had become heavily dependent on the plains bison for food, shelter, clothing, trade, and much more. In 1872 it was found that bison hides could be processed into commercial leather, and white hide-hunters immediately set out to meet that demand. Within a decade they had driven the millions of animals to the verge of extinction. The slaughter would have been unlikely, probably impossible, had railroads not provided the means to ship the hides and bones off to eastern factories. In one year near the end of the carnage, 1881–1882, the Northern Pacific shipped 2,250 tons of hides from the northern plains. Once the herds were gone, plains Indians had no true option but to turn to reservations and dependence on federal support. In effect the life blood of a people had bled away through the rail lines.
