Final answer:
The most accurate statement is that federal systems decentralize power between national and local governments, while unitary systems centralize power at the national level.
Step-by-step explanation:
Differences Between Federal and Unitary Systems
When comparing federal and unitary systems of government, their key characteristics revolve around the allocation and concentration of power. A federal system, such as the one in the United States, decentralizes power, sharing it between national and local governments as mandated by the national constitution. This system creates two relatively autonomous levels of government and provides balance between the forces of decentralization and centralization. On the other hand, a unitary system, like those found in France or Japan, centralizes power predominantly at the national level, with local and regional governments acting under the authority of the central government.
Therefore, the most accurate statement regarding these systems is that federal systems decentralize power between national and local governments (Option C), while unitary systems concentrate power at the national level, not distributing it equally between levels nor centralizing it exclusively at the local level.