P TR MR TC MC $30 $0 $15 $30 $30 $30 $25 $10 $30 $6 $30 $40 $15 $30 $90 $30 $60 $20 $30 $120 $30 $85 $25 $30 $150 $30 $115 $30 $30 $180 $30 $150 $35 9. That the firm is perfectly competitive is evident from its A) increasing marginal cost. B) increasing total cost. C) zero economic profits. | D) constant marginal revenue. E) absence of marginal values at Q = 0