Final answer:
An increase in aggregate demand leads to a higher (Option d) quantity of real GDP supplied, marked by a shift in the aggregate demand curve to the right, resulting in higher output and an inflationary pressure for a rise in price levels.
Step-by-step explanation:
Everything else remaining the same, an increase in aggregate demand increases the quantity of real GDP supplied. When aggregate demand increases, for instance, due to a surge in export sales, higher government spending, or tax cuts, it causes the aggregate demand curve to shift to the right. This shift leads to a new equilibrium with higher output, lower unemployment, and an inflationary pressure for price levels to rise. Such an increase in aggregate demand does not immediately affect the short-run aggregate supply, long-run aggregate supply, or the potential GDP. However, it does influence the quantity of real GDP that suppliers are willing to produce at the prevailing price levels.