The following graph shows the market for pollution when permits are issued to firms and traded in the marketplace. A graph of price, Price of Pollution, versus quantity, Quantity of Pollution, shows a vertical supply curve, Supply of Pollution Permits, which extends from Q = 50, a demand curve, Demand for Pollution Permits, descending linearly from (0, 2000) to (100, 0), and a horizontal line that extends from P = 1000 to the intersection of the curves, which is at (50, 1000). Refer to Figure 10-7. In the absence of a pollution permit system, the quantity of pollution would be a. 75 units. b. 25 units. c. 50 units. d. 100 units