For questions 4 refer to the graph below, which illustrates Marginal Private Benefits, "Marginal Private Costs, " "Marginal Social Benefits, " and "Marginal Social Costs" in the market for "Good X." $ Marginal Social Costs = (Marginal Private Costs) + (Marginal External Costs) 10.20 8.10 Supply (i) (iii) = (Marginal Private Costs) 3.50 (ii) (iv) Demand 2.10 = (Marginal Private Benefits) 1.00 = (Marginal Social Benefits) 0 quantity 220 900 1,250 0 4. Based upon this graph, it appears as if this good A. is a "club good." B. is sold by a firm with substantial market power. C. generates a positive externality. D. generates a negative externality