3. The pollution problem described below involves marginal benefits and marginal external costs where: MB = 60-30, MEC = 20, and we'll assume that MAC is just minus MB. Starting from a situation with no prior control on pollution by government, indicate the following: a. The initial level of pollution b. The optimal level of pollution c. If a CAC regulatory instrument were applied that reduced pollution to the optimal level, what would be the total benefit, the total abatement cost, and the net benefit (in dollars)? Air pollution from power plants 55 50 as MB, MEC 25 15 10 0 3 91912 13 14 15 17 18 19 20 THOUSAND TONS OF SOMONTH