A、It is because fast food restaurants are fast, informal, and inexpensive. B、It is because people can easily find fast food rest

The favorite food in the United States is the hamburger. The favorite place to buy a hamburger is a fast food restaurant. At fast food restaurants, people order their food, wait for a few minutes, and carry it to their tables themselves. People also take their food out of the restaurant and eat it in their cars or in their homes. At some fast food restaurants, people can order their food, pay for it and pick it up without leaving their cars.
    There are many kinds of fast food restaurants in the United States. The greatest in number sell hamburgers, French fries and so on. They are popular food among Americans. Besides, fast food restaurants that serve Chinese food, Mexican food, Italian food, chicken, seafood and ice-cream are very many.
    Fast food restaurants are popular because they reflect American life style. Customers can wear any type of dress when they go to a fast food place. Second, they are fast. People who are busy do not want to spend time preparing their own food or waiting while someone prepares it. In fast food restaurants the food is usually ready before the customer even orders it. Finally most food in a fast food restaurant is not expensive. Therefore, people are able to buy and eat there often, while they may not be able to go to a more expensive restaurant very often.