The Conclusion That Oligopoly Is Inefficient Relative to the Competitive

The conclusion that oligopoly is inefficient relative to the competitive ideal must be qualified because

A) industry price leaders often select a price equal to marginal cost.
B) over time oligopolistic industries may promote more rapid product development and greater improvement of production techniques than if they were purely competitive.
C) increased output due to persuasive advertising may perfectly offset the restriction of output caused by monopoly power.
D) many oligopolists sell their products in monopolistically competitive or even purely competitive industries.