4. In the following figure, which part is representative of each of the following? a. A decrease in wage rates b. An increase in the price level c. A beneficial supply shock d. An increase in the price of nonlabor inputs SRAS, SRAS, + (a) SRAS, (b) SRAS, SRAST SRAS, SPAS, + 0 (a) SRAS, B 0 (b) SRAS SRAS, (c)