Final answer:
A Pigovian tax on toilet paper production should be equal to the difference between the marginal social cost (MSC) and the marginal private cost (MPC) per unit of output.
Step-by-step explanation:
A Pigovian tax is a tax imposed on goods or services that generate negative externalities, such as pollution. In the case of toilet paper production, the bleach used in the manufacturing process causes environmental damage when discharged into rivers and lakes. To bring about the efficient level of production, the government should impose a tax equal to the difference between the marginal social cost (MSC) and the marginal private cost (MPC) of production per unit of output.