Comparing the private and social supply curves, the social curve for a polluting firm lies:

1. The social curve includes a cost the private curve leaves out. 2. The social costs include the private costs plus the external costs of pollution. 3. Accounting for additional external costs of 100 dollars per unit gives the curve S social. 4. Requiring that payment shifts the entire supply curve up by 100 dollars. 5. So the social supply curve lies above the private one. _Source: OpenStax Principles of Microeconomics for AP Courses 2e (CC BY 4.0), Ch 12 'Environmental Protection and Negative Externalities'_