The statement that best explains the difference between the Mayan civilization and the Roman Republic is:
D. The Mayan civilization was led by a demigod monarch, and each Mayan city operated independently with its own culture and laws. The Roman Republic was a centralized system led by two consuls and a senate.
This statement highlights the fundamental differences in governance and political structures between the two civilizations: the decentralized and city-state nature of the Mayan civilization versus the centralized, republican framework of the Roman Republic.