The lesson of new classical economics for policymakers is that managing aggregate supply has an effect on real GDP only if change is unexpected.
Option a
Step-by-step explanation:
Aggregate Supply curve defines the relationship between the output quantity and the price levels. If short-run curve shifts to the right, GDP increases and price level decreases and if it shifts to the left, GDP decreases and price level increases.
The reason is as follows,
Since the Aggregate Supply curve at full employment level of output is vertical, any changes in Aggregate Demand will only affect price and not real GDP. However, any unexpected changes in Aggregate Supply will influence real GDP.