A unitary system of government is characterized by a central government that holds the majority of the power, with any administrative divisions (like states) operating under its authority. In a unitary system, the central government can grant and revoke powers to subnational entities as it sees fit.
Given the options you provided, the response that best aligns with a unitary system is:
C. States can establish rules that cities have to follow
This option implies that the states derive their powers from the central government and can pass regulations, which is consistent with the nature of a unitary system where local subdivisions differ in authority based on the central government's policies.
If you require more insight or further explanation on unitary systems of government, feel free to ask!