Which structure is marked by a single seller in the market?

The market structure characterized by a single seller is known as a monopoly. In a monopoly, one firm dominates the entire market, providing a unique product or service with no close substitutes available to consumers. This lack of competition allows the monopolist to have significant control over pricing, as they are the sole provider of the good or service.

In a monopoly, the barriers to entry are typically high, restricting other firms from entering the market. This could be due to factors such as high startup costs, control of resources, government regulation, or technology. As a result, the monopolist can maximize profits by setting prices above the marginal cost of production, leading to higher prices for consumers than in more competitive markets.

Other market structures, such as oligopoly, monopolistic competition, and pure competition, involve multiple sellers or significant competition that influences pricing and output decisions differently than in a monopoly. In oligopoly, there are a few large firms that dominate the market, while monopolistic competition features many firms competing with differentiated products. Pure competition consists of numerous sellers offering identical products, which generally leads to prices settling at the level of the marginal cost of production. Thus, the distinctive characteristic of a monopoly is solely the presence of one seller in the market.