The graph gives the death for infectious diseases in the united states between 1900 and 1996

  Improve health practices.

Explanation:

  As seen on the graph every time there was a discovery in the field of medicine the rate of death decreases considerably. So the first option given is the correct answer because by those discovers the infectious deceases could be controlled.

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necessary and proper clause. the congress shall have power to 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, or in any department or officer thereof.