Astride horses, american indians could hunt far more effectively in many parts of the west, especially among the vast herds of bison on the great plains. those bison were hunted not just for their meat but also their hides, which women processed into robes to feed a hungry market in the east and europe. horses thus expanded native trade and brought a flow of new items into their lives—a trade invigorated also because indians could travel so much farther and faster than before. as from the time of the first horse cultures in central asia, western indians exploited a new military potential. some groups quickly developed astonishing skills as mounted warriors and proceeded to expand their hunting and trading territories against weaker neighbors.

–elliott west
"the impact of horse culture”

according to the excerpt, which is true regarding the plains indians?

they were the first people to domesticate the wild horses indigenous to north america.
they traded with early spanish explorers for domesticated horses.
they used horses to hunt more efficiently and to increase the size of the areas they occupied.
they openly traded horses to neighboring tribes in exchange for agricultural products.