Final answer:
In a quick-serve restaurant, one of the basic functions is purchasing, which is essential to acquire supplies and ingredients necessary for operation.
Step-by-step explanation:
The basic functions of a quick-serve restaurant include a variety of activities that allow it to operate efficiently and serve food to customers in a fast and convenient manner. One of these basic functions is C. Purchasing. This involves acquiring the necessary ingredients, supplies, and equipment to prepare and sell the restaurant's food and beverage offerings. Purchasing is essential as it ensures the restaurant has everything it needs to function on a day-to-day basis and to meet customer demand.