Answer:
The correct answer is A
Step-by-step explanation:
Money multiplier is the amount of money which the banks generate with each dollar of the reserves. Reserves is defined as the amount of deposits which the Federal Reserve need the banks to hold or maintain and not lend.
As banking reserves is the ratio where the reserves to the aggregate amount of the deposits.
So, if the money multiplier decrease from 20 to 12.5, them the Fed increase their reserve ratio from 5% to 8%.