Answer: The correct answer is "All of these".
Explanation: All of these statements are TRUE.
Monetarism is an economic doctrine that studies the effects of variations in the money supply on the relevant economic variables (such as employment, prices or production).
Keynesianism is based on state interventionism, defending economic policy as the best tool to get out of an economic crisis. Its economic policy is to increase public spending to stimulate aggregate demand and thus increase production, investment and employment.