Which of the Following Statements About Keynes' Contribution to Macroeconomics

Which of the following statements about Keynes' contribution to macroeconomics is correct?

A) although he published his most important ideas about the economy long before the 1930s,few economists paid attention to Keynes until the Great Depression proved him correct.
B) Keynes argued that depressions and recessions were almost always caused by changes in the money supply.
C) Keynes argued that balancing the budget could be an effective way to cure a recession or depression.
D) all of the above
E) none of the above