What effects did the growth of railroads have on business and society

a: initiated standardized time and consolidation of materials
b: reduced numbers of businesses and increased transportation costs
c: decreased businesses through overuse of natural resources
d: reduced population and consumption along the railway lines.

I believe the answer is A) Initiated standardized time and consolidation of materials.
With the new railroads, suddenly the US seemed to shrink. People who went from one side of the country to the other wanted to be able to know what time it would be when they arrived, so standardized time was created. 
Hope this helps! Please let me know if I'm wrong :) 

River valleys were good places for hunting and fishing.