Which of the following is a common guideline in responsible serving policies?

Serving only one beverage at a time is a common guideline in responsible serving policies because it helps to monitor and control the amount of alcohol consumed by patrons. This approach encourages moderation, allows servers to gauge a customer's level of intoxication more effectively, and can minimize the risk of overindulgence. By focusing on one drink at a time, servers can also engage patrons in conversation, assess their behavior, and make more informed decisions about whether to serve additional drinks.

In contrast, providing unlimited beverages to patrons would significantly increase the potential for excessive drinking, while limiting service to certain hours could still lead to binge drinking if not managed with additional responsible serving practices. Avoiding food during service is not a responsible serving policy; in fact, serving food alongside alcohol is encouraged as it can help slow down alcohol absorption and promote a safer drinking environment.