How many doors are to be installed in each vestibule of the Wendy's restaurant?

The correct choice is based on the standard design and requirements for commercial establishments such as Wendy's restaurants. Typically, vestibules are designed to help manage airflow and regulate the internal climate, especially in food service settings where temperature control is crucial.

Having two doors in each vestibule serves multiple purposes. First, they provide an airlock effect that helps maintain the internal temperature by limiting the amount of outside air entering the dining area when customers enter or exit. Second, this design facilitates easier traffic flow, allowing one door to be used for entering and the other for exiting. This dual-door system also helps to minimize energy costs associated with heating and cooling, as it prevents drafts and maintains a controlled environment for both staff and patrons.

In contrast, single doors are often less effective in creating a stable interior environment in high-traffic areas like restaurants. Additional doors might lead to unnecessary complexity, particularly in smaller vestibule spaces. The two-door design is a balance between form and function, aligning with common practices in the fast-food industry.