Final answer:
The correct answer is A. Marginal revenue.
Step-by-step explanation:
The correct answer is A. Marginal revenue.
Marginal revenue refers to the additional revenue gained from selling one more unit. It can be calculated by subtracting the total revenue of selling n-1 units from the total revenue of selling n units. For example, if selling 4 units generates a total revenue of $100, and selling 5 units generates a total revenue of $120, then the marginal revenue of the 5th unit is $20 ($120 - $100).