What is the necessary and proper clause and what does it do?

 The Necessary and Proper Clause allows Congress "To make all   Laws which shall be necessary and proper for carrying into Execution the Powers, and all other Powers vested by this Constitution in the Government of the United States.

 Often called the “elastic clause,” the necessary and proper clause simply states that Congress has the power, “To make 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.

Explanation:

hygrometers and hair thermometers (often found as part of hygrometers/psychrometers) can be used to measure humidity. barometers are used to measure atmospheric pressure, while anemometers are used to measure wind speed. so the 2nd and 4th choices should be the correct answers.