The United States uses which form of government?

A parliamentary system features a government where the executive branch derives its legitimacy from the legislature and is directly accountable to it. Countries like the United Kingdom exemplify this system, which contrasts sharply with the U.S. model that separates powers between branches and does not rely on legislative confidence for the executive's authority.

In a unitary government, power is centralized, and any administrative divisions (such as regions or provinces) have little to no independent authority. This model is seen in countries like France, where the central government retains supreme control, which is fundamentally different from the U.S. federal structure.

An oligarchy is a form of government where power resides with a small group of individuals or families, often ignoring broader democratic principles. The United States, with its elected representatives and numerous checks and balances, does not fit this description, as it promotes broader participation in governance.