Final answer:
The correct postoperative care instruction for a patient after a gastrectomy is to avoid carbonated beverages and the use of straws to prevent gas buildup.
Step-by-step explanation:
The student is asking about the appropriate postoperative care instructions for a client who recently had a gastrectomy, which is an operation to remove a part of the stomach. Among the options given, the correct instruction the nurse should include in the patient's care is c. "Avoid carbonated beverages and straws to prevent gas buildup." After a gastrectomy, it is important for patients to avoid behaviors that could introduce excess gas into the stomach, as their reduced stomach size can make gas particularly uncomfortable. Additionally, because their stomach is smaller, patients should consume smaller, more frequent meals rather than large ones.