请问银行之所以会increase reserve是因为市场上money总数增加了，所以比例不变的情况下，reserve也增加了吗？
问题如下图：
选项：
A. 
B. 
C. 
解释：
NO.PZ2016010801000083问题如下When the centrbank buys securities in the market:A.Banks will have recereserves.B.Money supply will creases.C.The interest rate will crease.C is correct.When the centrbank buys securities in the market, securities are replacecash in investor accounts, banks will have excess reserves, the money supply will increase, aninterest rate will crease.考点公开市场操作解析当央行在市场上购买证券时，证券被投资者账户（银行账户）上的现金所替代，银行就会有超额准备金，货币供应量就会增加，利率就会下降。所以C正确。银行准备金为什么会提高？ 题目说中央买证券，那是不是相当于放出货币，扩张政策，利率下降。那从存款准备金来说，准备金上升，不是紧缩政策吗？这不就矛盾了吗？
NO.PZ2016010801000083问题如下When the centrbank buys securities in the market:A.Banks will have recereserves.B.Money supply will creases.C.The interest rate will crease.C is correct.When the centrbank buys securities in the market, securities are replacecash in investor accounts, banks will have excess reserves, the money supply will increase, aninterest rate will crease.考点公开市场操作解析当央行在市场上购买证券时，证券被投资者账户（银行账户）上的现金所替代，银行就会有超额准备金，货币供应量就会增加，利率就会下降。所以C正确。MS和R的变动关系不是很明白
老师问下A为什么错
Arereserve,那么1/reserve更大，money supply不是更大吗？
请问市场上的钱变多了，利率为什么会下降？按照常识似乎应该是提高利率来维持汇率。
