Answer:
B) There is a lag between when policies are enacted and when the effects of those policies can be seen.
Explanation:
The issue that makes the central banking difficult for the Federal Reserve Bank -
The issue that makes central banking difficult , because if the lag between these two period is very large then we cannot determine whether the policy is working or not .
And other two are incorrect because money supply is controlled by the Fed , and it can increase and decreases the money supply .