15. In the U.S., which of the following does NOT belong to the Fed's policy options to increase the supply of US$? A. Cut interest rates so as to give Americans greater incentives to obtain loans from commercial banks. B. Reduce the minimum reserve requirement imposed on commercial banks so that they are likely to loan out more money C. Increase the government spending so that the federal government injects more money into the economy. D. Purchase more treasuries held by commercial banks so as to credit extra cash into their accounts ready for making bank loans