Which of the Following Is True

Multiple Choice

Which of the following is true?

A) In Bertrand oligopoly each firm believes that its rivals will hold their output constant if it changes its output.
B) In Cournot oligopoly firms produce an identical product at a constant marginal cost and engage in price competition.
C) In oligopoly a change in marginal cost never has an effect on output or price.
D) None of the preceding answers is correct.