The classical theory of aggregate supply where markets are perfectly f

The classical theory of aggregate supply where markets are perfectly flexible

a. may or may not be compatible with the Keynesian system.
b. is easily added the IS-LM framework of aggregate demand.
c. is fundamentally incompatible with the Keynesian system.
d. is consistent with the IS-LM framework if all shocks are to the IS curve.
e. none of the above.

ANSWER

C