Final answer:
The best method to ensure a pet has been appropriately fasted for surgery is to ask an open-ended question, specifically inquiring about the time of the pet's last meal to obtain clear confirmation.
Step-by-step explanation:
The best way to confirm whether a patient has been fasted ahead of a surgical procedure is by using an open-ended question that prompts the client to provide specific details regarding the last time the pet ate. Therefore, option A, "When did your dog last eat?" is the most effective approach. This question requires the client to give the exact time of the pet's last meal, providing clear confirmation of the fasting status rather than a yes or no answer, which could be misinterpreted or inaccurate if the client does not understand the fasting requirements.