Deposit Ratio Bank has US$ 1,000 billion in deposits and US$80 billion in required reserves, exactly meeting the 8% required reserve ratio. The central bank suddenly decides to increase the reserve requirement to 10%. What is the level of Deposit Ratio Bank's required reserve and excess reserve balances (in billions of US$) before taking any action? A. Required Reserves: 80 Excess Reserves: 0 B. Required Reserves: 80 Excess Reserves: -20 C. Required Reserves: 100 Excess Reserves: 0 D. Required Reserves: 100 Excess Reserves: -20