After the fall of the Yuan dynasty, Ming dynasty leaders tried to unify China by:
A. eliminating the written exams previously used to select leaders.
B. demanding that citizens follow traditional Chinese customs.
c. outlawing stories describing wars or turmoil from Chinese history.
D. abandoning conservative religious doctrines such as
Confucianism.
SUBM

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:

the answer would more than likely a.)falling crop prices  

hope the answer is right and ,either way have a nice day.