Which statement about pollution charges is correct?
a. A pollution charge is a tax imposed on the quantity of pollution that a firm emits.
b. A pollution charge gives a profit-maximizing firm an incentive to figure out ways to reduce its emissions—even when the marginal cost of reducing the emissions is greater than the tax.
c. A pollution charge is a tax imposed on the quality of pollution that a firm emits.
d. A pollution charge removes the incentive for a profit-maximizing firm to figure out ways to reduce its emissions.