Assume Money Supply Is $1,200 Billion, Bank Deposits Are $800

Assume money supply is $1,200 billion, bank deposits are $800 billion, and the reserve-deposit ratio is 10%.By how much is money supply likely to change if the Fed conducts an open market sale valued at $40 million?

A) -$100 billion
B) -$60 billion
C) +$40 billion
D) +$60 billion
E) +$100 billion