PLZZ HELP TEST DUE!!!

How did railroads help to ""conquer the West?""

(a.)Their expansion convinced Jefferson that Louisiana would be a good purchase.


(b.)They were used by the first group of Americans to travel west of the Rocky Mountains.


(c.)They connected the country by moving people and goods across great distances.


(d.)They were a platform the United States military used to conquer and control Indian tribes.