What characterizes an oligopoly?

An oligopoly is characterized by a market structure where a small number of firms dominate the industry. This small number of firms leads to a situation where each firm holds a significant market share and has the ability to influence the market's overall price levels and output decisions. The interdependence of these firms means that the actions of one firm can directly affect the others, leading to strategic behaviors such as collusion, price-setting above competitive levels, or engaging in differentiated competitive tactics to maintain their market positions.

In contrast, a market with many firms and free entry pertains more to a perfect competition scenario, where no single firm can influence prices due to the sheer number of competitors. Similarly, a scenario where no one firm can influence prices describes a completely competitive market, not an oligopoly. Lastly, a free market with unrestricted competition applies more to perfect competition as well, where many sellers and buyers exist, allowing for easy market entry and exit without the constraints seen in oligopolistic markets.