Which of the following made the greatest contributions to the american victory at yorktown? a. guerilla attacks led by francis marion. b. the aid of the french fleet c. the discovery that benedict arnold was a traitor. d. general greene's leadership

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:

d. william mckinley's southern upbringing him win.