Which of the following statements about the banking system is correct? Select one: O a. The real interest rate is the interest rate at which the central bank lends to commercial banks. O b. None of the answers listed is correct. O c. Commercial banks can increase base money by giving out new loans every year. O d. The policy rate is the rate at which the central bank lends to commercial banks. O e. The policy rate is determined by the supply and demand of the money market