What defines a monopoly in economic terms?

A monopoly is defined as a market structure where one seller dominates the supply of a product or service. This single seller has significant market power, allowing it to influence prices and output levels without competitive constraints. Unlike in competitive markets, where multiple sellers vie for consumer attention, a monopolist has no direct competition and can set prices higher than they would be in a more competitive environment. This dominance can arise from various factors such as control over essential resources, barriers to entry for other firms, or government regulations that grant exclusive rights to a single company.

The correct answer highlights the key characteristic of monopolistic markets: the lack of competition from other suppliers. In contrast to markets with many sellers or equal competition, a monopoly's unique position leads to a market structure where consumers have limited choices and potentially higher prices due to the absence of competitive pressure.