A) The firm’s marginal cost is equal to its average total cost.
B) The firm can earn positive economic profits.
C) The firm’s average total cost curve is above its marginal cost curve.
D) The firm produces at a level where average total cost is maximized.
For Explanation Click Here:
In the long run under perfect competition, firms operate where marginal cost (MC) equals average total cost (ATC). This ensures that firms earn zero economic profit, as price equals ATC.