When Designing a Policy to Reduce Polluting Emissions, Policymakers Are

When designing a policy to reduce polluting emissions, policymakers are unlikely to know with certainty what the marginal cost of abatement is for each firm. If policymakers set an emissions cap of X units, and issue tradable permits for this amount, then they

A) know the per- unit cost imposed on firms but do not know what the reduction in emissions will be.
B) are uncertain about both the amount of emission reduction and the cost.
C) know with certainty what the equilibrium permit price will be.
D) know with certainty what the reduction in emissions will be and at what cost.
E) know what the reduction in emissions will be but do not know at what cost.