When Congress raises income taxes, _______. A. the quantity of U.S. real GDP demanded increases and a movement up along the AD curve occurs B. the quantity of U.S. real GDP demanded decreases and a movement down along the AD curve occurs C. the demand for U.S. real GDP decreases and the AD curve shifts leftward D. the demand for U.S. real GDP decreases and a movement down along the AD curve occurs E. the demand for U.S. real GDP increases and the AD curve shifts rightward