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.