What does the Constitution establish for the U.S. government?

The Constitution serves as the foundational document for the U.S. government, explicitly outlining the structure of government and detailing its powers. It establishes the framework of the federal system, delineating the responsibilities and functions of the three branches of government: the legislative, executive, and judicial branches. Each branch is designed to operate independently while ensuring a system of checks and balances to prevent any one branch from becoming too powerful.

Additionally, the Constitution enumerates various powers granted to the federal government, as well as those reserved for the states and the people. This clear delineation of authority is crucial in maintaining the rule of law and ensuring the government operates within the limits set by the Constitution itself. Hence, the choice that reflects the main purpose of the Constitution in relation to the U.S. government is the one that refers to establishing its structure and powers.

The other options, while they may relate to the functions of the government, do not accurately describe the Constitution's primary role. For example, the political party system, economic policies, and foreign relations norms have evolved over time and are not directly established by the Constitution itself.