Figure 4.4.4 -Refer to Figure 4.4.4 Above. a Demand for Clean Air

Figure 4.4.4
-Refer to Figure 4.4.4 above. A demand for clean air, like the one in the figure is:

A) the actual demand in the market for tradable permits to pollute.
B) a demand derived from the differences in the willingness to pay for housing in cleaner or dirtier cities.
C) a demand approximately like the one estimated by the Environmental Protection Agency in the United States.
D) only a hypothetical demand.