What form of government must all states adhere to according to the U.S. Constitution?

All states in the United States are required to adhere to a republican form of government as mandated by the U.S. Constitution. This principle is rooted in Article IV, Section 4, which explicitly states that "The United States shall guarantee to every State in this Union a Republican Form of Government."

A republican form of government emphasizes the role of elected representatives and an elected leader (the president), in contrast to a direct democracy where decisions are made by popular vote. The republican structure provides a framework that balances individual rights and the collective good, allowing for a system of governance that enables citizens to have a voice in their government through representatives.

This requirement ensures that all states employ representatives to make laws and govern on behalf of the citizens, reinforcing the ideals of representative democracy and constitutional governance that are central to the American political system.

The other options, such as democracy (in the sense of direct democracy), dictatorship, and oligarchy, do not align with the guarantees and principles set forth in the Constitution, as they either concentrate power in the hands of a few, lack a structured electoral process, or do not uphold the foundational ethos of popular sovereignty found within a republic.