The Diagram Below Shows the Marginal Cost of Pollution Abatement

The diagram below shows the marginal cost of pollution abatement for two firms,Firm X and Firm Y.
FIGURE 17- 4
-Refer to Figure 17- 4.Firms X and Y have an emissions tax of $t imposed on each unit of pollution they produce.If Firm X chooses to abate QX units of pollution,the total cost of its abatement is

A) area beneath the marginal cost of pollution abatement curve.
B) tax amount t multiplied by the level of pollution abatement,QX.
C) tax amount t multiplied by the maximum possible level of pollution abatement.
D) area beneath the marginal cost of pollution abatement curve up to QX.
E) area below the horizontal line at t and above the MC of pollution abatement curve.