Figure 13-5 A graph of Cost versus Quantity; cost is on the vertical axis and quantity is on the horizontal axis. The graph shows three cost curves as follows: The MC curve; a U-shaped curve that decreases initially, then reaches a minimum, and then increases. The AVC curve; a U-shaped curve that begins at a slightly higher cost than the MC curve, decreases and reaches a minimum at the intersection of the increasing portion of the MC curve, then increases. The ATC curve; a U-shaped curve that begins at a considerably higher cost than AVC curve, reaches a minimum at the intersection of the increasing portion of the MC curve, then increases. The minimum points of the MC, AVC, and ATC curves are labeled on the horizontal axis accordingly: A, B, and C; the top portion of the MC curve has a point labeled D on the horizontal axis as well. Refer to Figure 13-5. The efficient scale of production occurs at which quantity? a. A b. C c. D d. B