I have been stuck on this question, i would appreciate some help, thank you. Please list answer as A B C or D

Figure 13-9 The figure below depicts average total cost functions for a firm that produces automobiles. Average Total Cost (9) ATCo ATCo ATCA ATCD M N Quantity of Automobiles per day Refer to Figure 13-9. Which curve represents the long-run average total cost?Refer to Figure 13-9. Which curve represents the long-run average total cost? A ATCB B ATCc C ATCD D ATCA