According to Chamberlin, the Fact That in the Long Run

According to Chamberlin, the fact that in the long run average total cost exceeds its minimum value under monopolistic competition is

A) the social cost of monopolistic competition.
B) the most important reason for why monopolistic competition is not efficient.
C) part of the cost of producing different products for consumers.
D) actually beneficial because it makes adjustments easier when demand increases.