Assume that the reserve requirement for demand deposits is 20 percent, that banks hold no excess reserves, and that the public holds no currency. if the banking system has limited reserves and the centrat bank sells $10,000 worth of government securities to commercial banks, the total money supply will
(a) increase by $10,000
(b) increase by $50,000
(c) decrease by $10,000
(d) decrease by $50,000
(e) not change