Arrange the following market structures in order of increasing market power held by firms: A) Perfect Competition → B) Monopolistic Competition → C) Oligopoly → D) Monopoly.

Market structures can be arranged based on the power firms have to influence prices and control the market. In perfect competition, there are many firms, and none can set prices; they can only accept the market price. As we move to monopolistic competition, firms have slightly more power because they sell differentiated products, allowing them to set their prices a bit higher. In an oligopoly, a few firms dominate the market, and they can influence prices by working together or competing against each other. Finally, in a monopoly, one firm has complete control over the market, allowing it to set prices without competition.