Refer to the following balance sheet of a banking system. The required reserve ratio is 20%.
If the central bank issues newly printed banknotes worth $200 million, the cash held by the non-bank public will increase by $100 million and the money supply will increase by $500 million. The total amount of excess reserves in the banking system will then be __________.
A. $100 million
B. $120 million
C. $280 million
D. $400 million