When a monopolistically competitive industry is in long-run equilibrium, the excess capacity in an individual firm is indicated by the difference between... O a. The output at which ATC is at a minimum and the output at which marginal revenue is equal to marginal cost. b. The output at which ATC is at a minimum and the output at which price equals marginal cost. O c. Price and marginal cost. O d. Zero and the output at which the demand curve is tangent to the ATC curve. O e. Price and average cost