Producing Paper Creates Pollution

Producing paper creates pollution. There is no externality in the consumption of paper. The efficient quantity of paper is when the

A) marginal social benefit of paper is equal to zero.
B) marginal private cost of the pollution from making paper is equal to zero.
C) marginal social cost of the pollution from making paper is equal to zero.
D) marginal social benefit of paper is equal to the marginal social cost of paper.