Final answer:
Marginal cost best describes the additional revenue associated with selling an additional unit of output.
Step-by-step explanation:
The additional revenue associated with selling an additional unit of output is best described by marginal cost.
Marginal cost is calculated by taking the change in total cost (or the change in variable cost) and dividing it by the change in output. It represents the cost of producing one additional unit of output.
A firm can compare the marginal cost to the additional revenue it gains from selling another unit to determine if the marginal unit is adding to profit.
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