Which of the following is true?

a. Keynesians advocate increasing the money supply during economic expansions but decreasing the money supply during economic recessions.

b. Monetarists advocate increasing the money supply during economic recessions but decreasing the money supply during economic expansions.

c. Keynesians argue that the crowding-out effect is rather large.

d. Monetarists argue that the crowding-out effect is rather large.