8. One way to think about the Fed's ability to change the nation's MI money supply is by thinking about its effects on the excess reserves within the banking system as a whole. In short, anything that increases excess reserves will tend to increase the money supply; anything that decreases excess reserves will tend to decrease the money supply. With that in mind, what would tend to happen to excess reserves in the banking system, and the MI money supply, if the Fed a) lowers the required reserve ratio. b) raises the required reserve ratio. c) buys U.S. securities on a mass scale. d) sells U.S. securities on a mass scale. Make sure to briefly explain why