Final answer:
Congress's authority is based on the Constitution, including enumerated, implied, and inherent powers, which allow it to function and regulate various aspects such as interstate commerce, reflecting the principle of federalism and popular sovereignty.
Step-by-step explanation:
The Constitution gives Congress the power to pass laws needed to carry out its other powers. Interstate commerce deals with trade and business across state lines. Federalism implies shared power between national and state governments. The authority of government comes from the people. This is called popular sovereignty (We the People). An interest group seeks to influence public policy. One example of this would be a lobbyist.
Congressional powers can be divided into three types: enumerated powers, which are explicitly stated in the Constitution; implied powers, which are not specifically detailed but are inferred as necessary to achieve the objectives of the national government; and inherent powers, which are assumed to exist simply because the United States operates as a sovereign nation.