Which market model assumes the least number of firms in an industry?

The market model that assumes the least number of firms in an industry is the monopoly model. In a monopoly, a single firm dominates the market, controlling the entire supply of a product or service, which allows it to exert significant pricing power. This structure contrasts sharply with models like perfect competition or oligopoly, which involve multiple firms competing in the market. Consequently, monopolies can lead to less consumer choice and potential market inefficiencies.