Economics Question - Excess Capacity?

The aim is to compare the situation between the perfect and imperfect market. In the imperfect market with market power or in this case monopolistic competition, price is larger than marginal cost. The demand is downward sloping, and the marginal revenue curve is under the demand curve.This causes higher price with less output. Even in the long run, it will produce at average total cost,but higher than its minimum point. That means higher cost even in the long run.