The Diagram Below Shows the Supply and Demand Diagrams for the Competitive

Multiple Choice

The diagram below shows the supply and demand diagrams for the competitive market for honey in one region.MC₀ represents private marginal cost and MB₀ represents private marginal benefit. FIGURE 16-3
-Refer to Figure 16-3.Assume there are two types of firms in this region - beekeepers that produce honey and orchard keepers that produce peaches.The bees provide a benefit to the orchard keepers by pollinating their peach trees.If the external marginal benefit is $4 per unit of honey,then what is the allocatively efficient output?

A) 40 kg
B) 60 kg
C) 80 kg
D) 100 kg
E) 120 kg