This region in South America has faced all of the following challenges recently except:

A: Harsh rule by military rulers

B: Difficulty controlling and developing natural resources

C: Recent colonization by European nations

D: Extreme gaps between rich and poor

I would say C

Explanation:

I don't know what region you are talking about, but I do believe that European nations have not taken over any region recently.

Unless you mean relative to your time period which would probably be A since they have been mining diamonds since 1700s.

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:

for hobos it was a very hard time most hid on the sides of the railroad tracks causing people to get bulls and get them off sometimes causing in fatal death they couldnt get people to give them money because the   people were also in need of money