a. marginal cost 1. the goal of a firm b. marginal revenue 2. the total cost per unit of production C. profit maximization 3. the change in total cost that results from one more unit d. fixed costs of production e. variable costs 4. the period over which some costs are fixed and some are variable f. average total cost 5. the fixed cost per unit of production g. average fixed cost 6. the variable cost per unit of production h. average variable cost 7. costs that vary with the level of production i. total cost 8. the change in total revenue that is gained by producing j. short run and selling one more unit