Answer: Fast food restaurants that compete at selling hamburgers are an example of monopolistic competition.
Explanation: In monopolistic competition, there are many sellers in the market who offer similar but not identical products. Each seller has a degree of control over the price of their product because they differentiate it from their competitors through branding, quality, location, or other factors. Fast food restaurants compete in a monopolistically competitive market as they differentiate their products by using unique recipes, branding, and other marketing tactics.