The correct answer is C. New towns sprang up in places that were not near rivers or canals because they did it along newly laid railroad tracks. Railroads could be built almost anywhere, and they constituted a fast commercial connection with other cities, so the water flows were not necessary anymore.
The railroad began to extend from the East Coast towards the center of the country, crossing later the Mississippi, penetrating arid zones without great amount of rivers. But the railroad functioned as a connection between these zones and the big cities of the East Coast, so the settlers could project their own settlements based on the commercial and social advantages that the railroad granted them.
