When a Negative Externality Is Present in a Market,when a Quota

When a negative externality is present in a market,when a quota is imposed,it is:

A) efficient,because the market consumes the efficient level.
B) not efficient,because individuals' net benefit of the amount set by the quota are different.
C) efficient,because the net benefit of everyone at the amount set by the quota is equal.
D) not efficient,because the marginal cost outweighs the marginal benefit for too many consumers at the amount set by the quota.