The Marginal Social Cost of Producing a Good or Service

The marginal social cost of producing a good or service is the

A) cost of producing an additional unit borne by the producer.
B) cost of producing an additional unit borne by people other than the producer.
C) sum of the marginal private cost and the marginal external cost.
D) same as marginal external cost.
E) sum of the marginal private cost and the marginal external cost minus the marginal social benefit.