Answer: Option (D) is correct.
Explanation:
The economic efficiency is achieved at a point where demand curve and supply curve intersects each other. This point is known as market equilibrium. The area under the demand curve and above the equilibrium price level is known as consumer surplus.
The area above the supply curve and under the equilibrium price level is known as producer surplus.
Hence, the combine area of consumer surplus and producer surplus have to maximized to have a economic efficiency in an economy.