The correct answer is: B. Optimum
An optimum firm is a firm that enjoys the lowest average cost of production. This is achieved when the firm produces at the point where the marginal cost curve intersects the average cost curve. At this point, the firm is producing at the most efficient level and is therefore able to produce goods at the lowest possible cost.
A representative firm is a firm that is typical of all firms in a particular industry. A small-scale firm is a firm that is relatively small in size compared to other firms in the industry. An equilibrium firm is a firm that is producing at the point where the demand curve for its product intersects the supply curve for its product.
Here is a diagram that illustrates the concept of an optimum firm:
[Diagram of a firm’s cost curves]
The average cost curve (AC) is the sum of the firm’s average variable cost curve (AVC) and its average fixed cost curve (AFC). The marginal cost curve (MC) intersects the AC curve at the point where the AC curve is at its lowest point. This is the point of optimum production for the firm.
I hope this explanation is helpful! Let me know if you have any other questions.