Which of the following best explains why territorial expansion was so important to the classical civilizations?
a. territorial expansion was necessary because of the growing populations of the classical civilizations.
b. territorial expansion was an important way to ensure the success of sophisticated mail-delivery systems.
c. territorial expansion was necessary to contact and connect to the other classical civilizations.
d. territorial expansion served as a way to divide regions between the several rulers who oversaw parts of each classical civilization.