A steelmaking plant pollutes the air and water so __________.
A. The marginal social cost of producing steel exceeds the marginal private cost by the amount of the marginal external cost.
B. The marginal social cost of producing steel is less than the marginal private cost by the amount of the marginal external cost.
C. The marginal private cost of producing steel equals the marginal external cost plus the marginal social cost.
D. The marginal private cost of producing steel minus the marginal social cost equals the marginal external cost.