Which conditions in the East most likely helped cause the changes throughout the U.S. transportation systems shown on the maps?

— ExhibitC

Which conditions in the East most likely helped cause the changes throughout the U.S. transportation systems shown on the maps?
A . respect for Mexico’s land claims in the West
B . destruction caused by war
C . the emancipation of all slaves
D . laws that protected Native Americans’ land rights
E . increasing population and growing industries

Answer: E