Which of these would be most useful in studying the effect of germs exchanges between the new and old worlds?

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:

in which two ways were the northeast woodland indians and the southeast indians similar? both collaborated to form the iroquois confederacy. both cultivated the crops of corn, beans, and squash. both lived in rich environments of swamps and rivers. both lived in tree-bark dwellings called wigwams. both expected men to hunt, while women farmed.

the answer is