If Pollutants Emitted by Firms in the Steel Industry Increase

Multiple Choice

If pollutants emitted by firms in the steel industry increase, but there is no increase in the costs borne by these firms, you could conclude that

A) pollution is not a serious problem in this industry.
B) the consumers of steel are unwilling to bear the costs of pollution generated from steel production.
C) pollution is an externality in this market, since producers and purchasers of steel do not bear the full costs of the pollution.
D) pollution creates an external benefit rather than an external cost in this case.