The correct option is C
This railroad was considered the greatest American technological feat of the 19th century. It served as a vital link for industry, commerce and travel, uniting the East and West halves of the late nineteenth century of the United States. The transcontinental railroad ended quickly with the romantic lines of diligence, much slower and riskier, that had preceded it. The subsequent advance of the so-called "manifest destiny" and the proliferation of the "iron horse" through the lands of the indigenous natives greatly accelerated the fall of the great Indian culture of the great plains.
