During the postclassical era, empires grew to larger sizes than they had in the past. which of these factors contributed to this trend

the answer is a. laws were enacted in the aftermath of the plot to make it harder to free slaves,increasing sectionalism

answer: the time zones used to be whatever the local authority wanted them to be. one town might have 6am whenever the sun came up and another town had 6am 10 minutes later.  

the trains had a hard time when their orders said to be at a certain point at 6am.  

6am, but who's 6am.  

the railroads got together and set the time zones more or less along the longitude lines across the country.

explanation: