Regulations require that emissions of carbon monoxide be limited to 1,000 tons per 100 square miles for all regions of the nation. If the marginal external cost of the emissions varies among regions in the nation, then the regulations will:
A. achieve an efficient amount of pollution abatement.
B. be likely to achieve more than the efficient amount of abatement in some regions, but less than the efficient amount in others.
C. achieve more than the efficient amount of pollution abatement
D. achieve less than the efficient amount of pollution abatement.