Answer: D. Necessary and proper clause in Article I
Explanation: Article I of the United States Constitution establishes the legislative arm of the federal government, which is the United States Congress. Congress is a bicameral legislature consisting of the Senate and the House of Representatives. Article I grants Congress various powers and the ability to pass laws "necessary and proper" to carry out those powers.
Section 8 specifically talks about the powers of Congress and that Congress is vested with making all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States.
This means Congress has the power to make laws which would help in the execution of vested powers such as the Clean Water Act which regulates amount of pollutant in water bodies.