In which market structure does no single company control prices?

The competitive market is characterized by many buyers and sellers, resulting in no single entity having the power to control prices. In this market structure, individual firms are price takers; they must accept the market price set by the forces of supply and demand. Because numerous businesses compete for customers by offering similar products or services, this competition ensures that prices remain low and are determined by the collective actions of all participants in the market.

In contrast, other market structures such as monopolistic, oligopolistic, and duopoly involve fewer firms. In a monopolistic market, a single company can significantly influence prices due to a lack of direct competition for its unique products. In an oligopolistic market, a few dominant firms may collude or compete in ways that can affect prices. A duopoly, a specific case of oligopoly, involves only two firms that have the potential to set prices based on their interactions.

Therefore, the defining characteristic of a competitive market is the absence of price control by any single entity, which is why this answer is correct.