When the economy is operating at potential GDP, an unannounced decrease in the rate of growth of the money supply intended to reduce inflation will most likely lead to. lower inflation and:（）
A. a decrease in output in both the short run and the long run.
B. no change in output in both the short run and the long run.
C. a decrease in output in the short run, and lower inflation but no change in output in the long run.
参考答案：C
解析：
In the aggregate supply-aggregate demand model, an unannounced decrease in the growth rate of the money supply will decrease output and prices in the short run, but in the long run inflation will decrease more and output will return to the full-employment level as short-run aggregate supply increases in response to the decrease in inflation.