Answer:
average total cost per unit is not at its lowest possible cost
Explanation:
A monopolistic competition is defined as such a market where many different firms or companies sells various differentiated products. Here the firm has some control on the price of the product. It is a market structure of considerably no price competition.
The monopolistic firms are not productive enough because the output is very less than the optimum level of the society as the average total cost of the producer per unit is not at the lowest possible cost.