5 - Long Run for the Firm LEARNING OBJECTIVE: Using a graph, identify production and cost in the long run. Consider the long-run cost curve below. The downward-sloping portion on the left side illustrates Cost (in dollars) ATC Long-Run Cost Curve ATC, ATC6 ATC 5 ATC, ATCA X 0 150 275 350 450 650 800 900 Quantity of Output O a.) constant cost industry O b.) minimum efficient scale c) economies of scale O d.) diseconomies of scale