The graph shows the marginal social benefit and the marginal social cost of pollution from a paper mill. A graph plots the Marginal Social Cost (MSC) and Marginal Social Benefit (MSB) of pollution on Quantity of pollution emissions (tons) along the horizontal axis and Marginal social cost, marginal social benefit along the vertical axis. The MSC of pollution curve stats at the origin and has a positive slope. The MSB of pollution curve starts at 1,600 dollars on Marginal social cost, marginal social benefit and has a negative slope. The curves intersect at 4 tons on pollution emission, 800 dollars on marginal social cost, marginal social benefit. The MSC of pollution curve passes through the following coordinates as Quantity of pollution emissions (tons) and Marginal social cost, marginal social benefit: 3 tons, 600 dollars; 6 tons, 1,200 dollars; 8 tons, 1,600 dollars. The MSB of pollution curve passes through the following coordinates as Quantity of pollution emissions (tons) and Marginal social cost, marginal social benefit: 3 tons, 1,000 dollars; 6 tons, 400 dollars; 8 tons, 0 dollars. The market-determined quantity of pollution is _____ tons greater than the socially optimal quantity of pollution