Each of the Following Is Something That Economists Know About

Each of the following is something that economists know about business cycles, unemployment, and inflation in the short run except

A) that the basic Keynesian sticky-price model still provides a good guide to the basic determinants of the level of aggregate demand.
B) that the aggregate supply-Phillips curve diagram still provides a guide to the relationship between the level of real aggregate demand and the rate of price increase.
C) that the Phillips curve is very stable.
D) that aggregate demand is the principal determinant of the level of real GDP in the short run.