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Which supporting detail from the passage would be most important to include in a summary?
Until the 1800s, there was no such thing as standard time. Each local town had its own time, based on the position of the sun over the town. Times often differed between towns that were only a short distance apart. In the United States, for instance, there were over 300 different time systems

Why did this change? Railroads. With so many different times, it was impossible for people to know when to catch the train Accidents even resulted sometimes, when operators of trains using the same track had different times on their clocks. So, to make train travel possible, the world was divided into time zones, and times were standardized

A. Until the 1800s, there was no such thing as standard time


B. Accidents even resulted sometimes, operations of trains using the same track had different times on their clock


C. Times often differed between towns that were only a short distant apart


D. In the United States, for instances, there were over 300 different times systems.