Which of the following is true?

Multiple Choice

In Bertrand oligopoly markets, each firm believes that its rivals will hold their output constant if it changes its output.

In Cournot oligopoly markets, firms produce an identical product at a constant marginal cost and engage in price competition.

In Sweezy oligopoly markets, each firm believes rivals will cut their prices in response to a price reduction but will not raise prices in response to price increases.

In oligopoly markets, a change in marginal cost never has an effect on output or price.