Answer:
The correct answer is D. the firm has achieved the lowest possible average cost of production.
Step-by-step explanation:
The minimum efficient scale is called the value of production for which the average long-term cost is minimal and also coincides with the marginal cost.
On the minimum efficient scale it is said that we are in the smallest possible production in which a long-term competitive company would be interested in producing. Below that value, the company would go into losses and should close.
The curve of long-term average costs is obtained from the envelope of the infinite possible curves of short-term average costs for different plant sizes, that is, for different levels of capital. From this envelope, a U-shaped average cost curve is obtained, at which minimum, precisely, the minimum efficient scale is found.