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The accompanying diagram shows the supply and demand diagrams private marginal cost and MB0 represents private marginal benefit. 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 $2 per unit of honey, then what is the allocatively efficient output? A. 20kg B. 80kg C. 40kg D. 100kg E. 60kg