问题如下：
Which of the following is least appropriate about Country A, if Country A pegs their currency exchange rate with the dollar?
选项：
A.Country A should keep their inflation rate equal to USA
B.Country A should sell dollar reserve if their currency is less valuable.
C.Pegging exchange rate will decrease the volatility of money supply in Country A.
解释：
C is correct. Pegging exchange rate will increase the volatility of money supply in Country A, as it will has more volatile interest rate to keep inflation rate similar to USA.
考点：Pegging exchange rate
解析：Pegging exchange rate 会增加A国货币供给的波动性，从而使通货膨胀率与美国的通胀率保持一致。A选项不入选。
A国本币贬值的时候，A国政府就应该在外汇市场上买入本币，卖出外汇储备，所以B选项不入选。
但是这种情况下，A国的利率受到货币供给变化的冲击会更加明显，表现也更不稳定。所以C选项入选。
A国本币贬值的时候，A国政府就应该在外汇市场上买入本币，卖出外汇储备？为什么呀
