Of the following industries, which are perfectly competitive? For those that are not perfectly competitive, explain why

a. Restaurants
b. Corn
c. College education
d. Local radio and television

a. Restaurants are not perfectly competitive. Although cities typically have many restaurants for consumers to choose from, they do not sell identical products. They also differ in the services they offer their customers. Some restaurants have take-out windows, some have servers while others (McDonald's, Burger King) require customers to pick up their own orders.
b. The market for corn (and other agricultural commodities) is a perfectly competitive market. Each buyer and seller is small relative to the total market. Although there are varieties of corn (for example "number 2" corn) within these varieties one farmer's corn is indistinguishable from any other farmer's corn.
c. The market for a college education is not perfectly competitive. This is an example of a market that offers consumers (students) a differentiated product. Colleges and universities differ in size, amenities, quality of instruction, location, and many other factors.
d. Local radio and television markets are not perfectly competitive. Radio and television stations do not offer identical products. Some radio stations broadcast only classical music, while others play classic rock, alternative rock, country music, etc. Television stations also offer different programming including movies, sports, news, etc.