One Difference Between Oligopoly Firms and Firms That Are Monopolistic

One difference between oligopoly firms and firms that are monopolistic competitors is that:

A) the average total cost curves of monopolistic competitors are generally u-shaped, but for oligopoly firms they are not.
B) monopolistic competitors choose a level of output such that marginal revenue equals marginal cost, but oligopoly firms generally do not.
C) monopolistic competitors face lower costs on average than do oligopoly firms.
D) the interdependence among firms is highly significant in oligopoly markets, but not in monopolistically competitive markets.