NO.PZ2016010801000083
问题如下：
When the central bank buys securities in the market:
选项：
A.
Banks will have reduced reserves.
B.
Money supply will decreases.
C.
The interest rate will decrease.
解释：
C is correct.
When the central bank buys securities in the market, securities are replaced by cash in investor accounts, banks will have excess reserves, the money supply will increase, and interest rate will decrease.
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选项正确。
MS和R的变动关系不是很明白
