What is the difference between marginal cost and marginal revenue? a. marginal cost is the money earned from selling one more unit of a good. marginal revenue is the money paid for producing one more unit of a good. b. marginal cost is the money paid for producing one more unit of a good. marginal revenue is the money earned from selling one more unit of a good. c. marginal cost is the money a producer might make from one more unit. marginal revenue is the money a producer actually makes from one more unit. d. marginal cost is the money a producer actually makes from one more unit. marginal revenue is the money a producer might make from one more unit.