单选题 An increase in which one of the following monetary measures would best complement fiscal measures that are designed to stimulate aggregate demand during a period of high unemployment?

A. Reserve requirements.
B. Treasury securities held by the Federal Reserve.
C. The Federal Reserve's discount rate.

【正确答案】 B

【答案解析】The Fed increases its holdings of Treasury securities through open market purchases, which puts money into the system, which will increase aggregate demand. While the other tools are used to implement monetary policy, they will decrease demand as described.