13. If short-run equilibrium in the Mundell-Fleming model is represented by a graph with Y along the horizontal axis and the nominal exchange rate along the vertical axis, then the IS* curve: A) slopes downward and to the right because the higher the exchange rate, the higher the level of net exports and, therefore, the higher the level of income that equilibrates the goods market. B) is vertical because there is only one investment level that is consistent with the world interest rate. C) is vertical because the exchange rate does not enter into the IS* equation. D) slopes downward and to the right because the higher the exchange rate, the lower the level of net exports, and therefore, the lower the level of income that equilibrates the goods market.