Figure 11.4 depicts demand and costs for a monopolistically competitive firm. At Figure 11.4 the profit-maximizing output level: O A. the firm is earning a negative economic profit. O B. the firm is earning a zero economic profit. Firm-specific demand O C. the firm is making a positive economic profit. 8- ... O D. There is not sufficient information. 5-........... Average cost Marginal cost 3- Marginal revenue 100