The Net Benefit to Society from an Action Is Maximized

The net benefit to society from an action is maximized where the action's:

A) total social benefit exceeds total social cost by the greatest amount.
B) total social benefit minus total social cost equals marginal social benefit minus marginal social cost.
C) positive external effect minus negative external effect equals total private benefit minus total private cost.
D) marginal social benefit equals marginal private benefit, and marginal social cost equals marginal private cost.