In order to make their schedules more standard, what did the railroads do? A. Forced every train to leave its station on the hour
B. Allowed each train to set its own schedule
C. Divided the United States into time zones
D. Put the whole United States on the same time

Option C

Explanation:

After the completion of the railways, there was a big problem facing this sector, there was a disparity in time across the country; time was locally determined by some local solar time frame which were different from one locality to another. To tackle this issue,there need to be some sort of standard time. if not, there is no way to predict when moving passengers and freight,train will arrive; so some sort of coordinate to follow so that things work out right in determine and predicting schedules is needed.

In order to make their schedules more standard, the railroads divided the United States into time zones( the time zone was divided into four standard time zone)

The division of the United States into Standard time zones was first done by the railroads to end the confusion of dealing with thousands of local times.

both include an amendment process.