Suppose You Are an Economic Researcher, and You Have Access

Suppose you are an economic researcher, and you have access to detailed information about all of the firms in a given geographic area. You would conclude that the pollution reduction policy in that area is efficient if you observe that:

A) all firms produce approximately the same amount of pollution.
B) the cleanest firms are also the most profitable.
C) the marginal cost of reducing pollution is the same for all firms at current emissions levels.
D) all firms currently use the same pollution reduction technology.