The effect on the economy of tax reduction and simplification is
A. an increase in the quantity of real GDP supplied at every price level, and a shift in the long-run aggregate supply curve.
B. higher employment and real GDP but also a higher price level.
C. a decrease in consumption and investment spending, and a shift to the left of the aggregate demand curve.
D. a change in the costs to firms, as shown by the short-run aggregate supply curve shifting to the left marginal tax rate.