How did the introduction of the horse to North America by the Spanish change the lives of Native Americans? A. Southwestern Indians could plow their fields more quickly. B. Eastern Woodland Indians drove the Spanish off their lands. C. Plains Indians could travel farther and conduct more trade. D. Pacific Northwest Indians could hunt buffalo more efficiently.

With the introduction of the Spanish horses to North America by the Spanish, the Pacific Northwest Indians could hunt buffalo more efficiently. Also Plains Indians could travel further and conduct more trade. So for this question, option "C" and "D" are both correct. The Indians took great care of their horses as these horses were a kind of sacred and legendary creatures for them. The native Indians took great care while training the horses captured from the wild. The Indians considered them as an animal that symbolizes freedom.