Suppose, at a given interbank funds rate, there is an excess demand for reserves in the interbank funds market. If the central bank wants the interbank funds rate to stay at that level, then it should undertake an open market ________ of bonds, everything else held constant. If the central bank does nothing, however, the interbank funds rate will ________.
a. purchase; increase
b. purchase; decrease
c. sale; increase
d. sale; decrease