this is a multiple choice question

In which of the following situations will the outcome be \"optimal\" (specifically, Pareto optimal) in the equilibrium for the participants that are specified in the situation? a) each firm in a Cournot model of duopoly chooses its output to maximize its own profit, taking the output of the other firm as given; b) each firm in a Bertrand model of duopoly chooses its price to maximize its own profit, taking the price of the other firm as given; c) each consumer in a market chooses his optimal bundle given his income and the prices, without regard for the decisions of other consumers; d) the outcome is optimal in every one of the above situations; e) the outcome will not be optimal in any of the above situations