How was Classical Persia's extensive network of roads important to its civilization?
A) it allowed Persia to supply all of its own economic needs without needing to expand its borders.
B) it helped Persian religious leaders monitor the empire to make sure no minority religions were being practiced.
C) it allowed Persian military forces to efficiently protect the empire's many independent city-states.
D) it helped Persia create a feeling of unity among citizens across its empire's vast territory.