The rail road did so much in the growth. They had supported the west side and made a great economic growth. And not only this, but because of rail road, it would make it alot easier to transport things. So, based from you option's listed above, you correct answer to this question would be "<span>Made it easier to move products from the interior of the country to the cities".This is something that rail roads also played a great role in doing, help to move other item's within a constant speed.
I'm literally learning this now in APUSH. In 1914 which is the era of the gilded age people were dependent on railroads and oil. Thanks to help from Carnegie (and the other 4 men) (around 1914) and steel, the US economy rose back from its divided chaos.
