The Diagram Below Shows the Private and Social Marginal Costs

The diagram below shows the private and social marginal costs (MC_P and MC_S) and the social marginal benefits (MB_S) of producing disposable diapers. FIGURE 17-2
-Refer to Figure 17-2.The net social benefit derived from the production and use of the last unit of disposable diapers is

A) at a minimum at Q₀,because MC_S exceeds MC_P.
B) at a maximum at Q₀,because that is where MC_S equals MB_S.
C) at a maximum at Q₁,because that is where MC_S equals MB_S.
D) zero at Q₀,because that is where MC_S equals MB_S.
E) zero at Q₂,because that is where the externality is fully maximized.