Which of the 6 geography elements do you think is the most important

i believe the answer is d.

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 main objectives of the progressive movement were eliminating problems caused by industrialization, urbanization, immigration, and political corruption.