Final answer:
Firms produce homogeneous products in a perfect competition market structure, which is characterized by many firms and free entry and exit. The correct answer is option c.
Step-by-step explanation:
In perfect competition, firms produce a homogeneous product. This type of market structure is characterized by many firms, freedom of entry and exit, and a homogeneous product. In contrast, a monopoly entails a single firm that produces a unique product without close substitutes, differentiated oligopoly is a market where a few firms have a dominant position with differentiated products, and monopolistic competition involves many firms that produce similar but slightly differentiated products. Oligopolies may also compete on price, advertising, and other product differences, whereas in monopolistic competition, firms have a degree of market power due to product differentiation. Therefore, it is in perfect competition where firms produce homogeneous products.