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Suppose the economy is initially at the natural level of output. Suppose there is an decrease in the price of oil. Explain your answers but no need to draw. a) What will be the effects of this on IS, LM, AD and AS in the short-run? b) What will be the effects of this on IS, LM, AD and AS in the medium run? c) What monetary policy action will prevent a change in output when this happens in the short run