Given That Different Firms Typically Have Different Costs of Pollution

Given that different firms typically have different costs of pollution reduction,

A) tradable pollution permits will help to reduce the total costs of pollution abatement.
B) tradable pollution permits will help to reduce the marginal costs of pollution.
C) it is clear that only a moral solution can actually achieve pollution reduction.
D) there is a role for government to establish absolute limits on pollution.
E) the optimal emissions tax is thus easier to compute.