The best answer for this question would be answer choice C, The economic opportunities to be found, due to the vast territory in the west with abundant resources people would takes years to travel to the west just for new promise in their lives and hope for luxurious resources to be uncovered. One example of this would be the rush for gold in the west in California which was in 1848. People especially before railroads would take years to travel out west just for a better chance in life.
