Choice "B" is correct. As shown below, an increase in aggregate demand causes the equilibrium price level to rise and equilibrium output (real GDP) to increase.Choice "c" is incorrect. As shown above, equilibrium output increases, not decreases.
Choice "d" is incorrect. As shown above, the equilibrium price level increases, not decreases.
Choice "a" is incorrect. As shown above, the equilibrium price level increases, not decreases.
