What is the primary purpose of the U.S. Constitution?

The primary purpose of the U.S. Constitution is to provide a legal framework for the government. This foundational document establishes the structure, functions, and limits of government, outlining the separation of powers among the executive, legislative, and judicial branches. It also serves to protect individual rights and liberties, ensuring that government authority is exercised within the bounds of law.

While other options mention important aspects of government function, such as trade regulation or tax rates, these elements are details that fall under the broader scope established by the Constitution. For example, the authority to regulate trade and impose taxes comes from the powers granted to Congress within the Constitution, making these aspects secondary to its primary role of structuring the government and protecting citizens' rights.