The statement that is not accurate is - C. It caused the decline of cities in the South and West.
The transcontinental railroad system was of great benefit for pretty much all of the country, and it didn't caused decline of cities in any area of the country, especially not in the western part, because the western part was one of the areas that benefited the most by it. This railroad system managed to lift the economies of lots of places, and made the trade and transport throughout the country easier, and more economically justified.