20) The theory of oligopoly suggests that A) entry into the industry is an important force preventing the exploitation of market power by existing B) oligopoly may be the best of the feasible alternative market structures when mayor sode comomics exist C') Innovation is weak when there is no price compete on. D) game theory is interesting theory but not useful for real corporate managers, () the tendency toward joint maximization of profits is greater for a large number of sellers than for a small number of sellers