Which one of the following factors contributed to the decline in real output during the Great Depression?

a. deflation, which changed the terms of long-term contracts and discouraged long-term exchange
b. inflation, which reduced the value of the dollar and eroded the savings of the elderly
c. stable monetary policy, which caused business decision makers to lose confidence in the Fed's ability to fine-tune the economy
d. establishment of the Federal Deposit Insurance Corporation

A