Answer: B or - 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.
Explanation: Marginal revenue is the income gained by selling one additional unit, while marginal cost is the expense incurred for selling that one unit. Each measure the incremental change in dollars between varying levels of sales to determine at what level a company is most efficiently producing and selling goods.