Final answer:
Oligopolies are characterized by interdependence among firms, meaning that the decisions of one firm directly affect other firms within the industry. This concept influences how firms behave in terms of competition and cooperation.
Step-by-step explanation:
Oligopolies are characterized by interdependence among firms within the industry. When one firm in an oligopoly changes its price or level of output, it directly affects other firms. This means that firms must consider the decisions of their competitors when making their own decisions about pricing, output, advertising, and other factors. The concept of interdependence in oligopolies is important because it influences how firms behave in terms of competition and cooperation.