microeconomics question:

146. (Figure: Efficiency and Pollution) Look at the figure Efficiency and Pollution. An optimal Pigouvian tax of can move this market to the socially optimal quantity of pollution. A) $5 B) $15 C) $25 D) $45Figure: Efficiency and Pollution Marginal social cost, marginal social benefit MSC $25 22 20 15 12 NOVO MSB 0 5 10 15 20 25 30 35 40 45 50 55 Quantity of pollution emissions (tons)