What did the study in a pennsylvania forest reveal about the environmental effects of using ddt? a. ddt caused the birds in the forest to disappear. b. ddt killed aphids that ate forest leaves. c. ddt killed ladybugs, which caused the aphid population to rise. d. ddt killed aphids, which caused the ladybug population to rise.

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:

this act gave the federal government the power to relocate any native in the east to territory west of the mississippi river.