As the Fed maintained interest rates at near zero during 2008-2012, a. the economy recovered and the unemployment rate fell to normal levels. b. stock prices declined during 2010-2012, causing the economy to remain weak. c. the earnings senior citizens derived from saving deposits and other forms of savings rose substantially, leading to higher incomes and a strong increase in aggregate demand. d. households and businesses held larger money balances and the velocity of money fell substantially