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Why is the supply function for federal funds flat (horizontal) at the level of the discount rate? a. Because the Fed refuses to lend money to commercial banks at or above the discount rate, b. Because the Fed wants to keep the discount rate above the interest rate it pays on bank reserves. c. Because the Fed wants to keep the discount rate above the equilibrium federal funds rate. d. Because the Fed supplies loans to commercial banks at the discount rate as much as banks want to borrow. e. Because if the equilibrium federal funds rate is above the discount rate, banks will borrow from other banks rather than from the Fed