Which of the following claims concerning the importance of effects that explain the slope of the U.S. Aggregate demand curve is correct? A. The exchange-rate effect is relatively small because exports and imports are a small part of real GDP. B. The interest-rate effect is relatively small because investment spending is not very responsive to interest rate changes. C. The wealth effect is relatively large because money holdings are a significant portion of most households" wealth. D. None of the above is correct.