Which of the following industries is a real-world example of oligopolies?

The automotive industry is a real-world example of an oligopoly. In this industry, a few major companies (such as Ford, General Motors, and Toyota) dominate the market, and their actions can significantly influence prices and production levels. The other industries you mentioned (fast-food restaurants, agricultural vendors, and local electricity companies) would represent different market structures, such as monopolistic competition or monopoly, rather than an oligopoly.