The Figure Below Shows the Demand and Supply Curves in the Market

The figure below shows the demand and supply curves in the market for elementary education.Figure 13.1
In the figure,
D: Private demand curve for elementary education
D + s: Demand curve which includes public benefits
S: Supply curve of education
Price and Quantity have been taken on vertical and horizontal axes respectively.
-Figure 13.1 represents a situation of:

A) positive externalities.
B) negative externalities.
C) excess capacity.
D) optimal provision of a public good.
E) comparative advantage.