List the three different ways in which oligopoly firms may behave

Following are the three different ways in which oligopoly firms may behave:
(i) Firms may collude together and decide not to compete with each other and maximise total profits, as in collusive oligopoly.
(ii) Under non-collusive oligopoly, firms decide not to collude and hence decide to compete with each other through non-price competition.
(iii) Firms may produce differentiated products, having their own distinguishing characteristics, as in imperfect oligopoly.