According to the monetarist proponents, mark the correct answer:

a) The Fisher equation is their basic economic instrument.
b) The government must intervene by activating the economy with public investments.
c) Its main representative was Keynes.
d) The market must be planned.
e) They advocate a planned economy.
a) Only a.
b) Only b.
c) a and b.
d) a and c.
e) All.