Final answer:
The nurse should document the patient's ability to self-feed and mark the nursing diagnosis as resolved, thereby updating the care plan to reflect the patient's current status.
Step-by-step explanation:
The student's question pertains to the appropriate actions a nurse should take when a patient has met a specific outcome, in this case, self-feeding. If the nurse evaluates that the patient has met the outcome of feeding himself independently, the correct action is to document the patient's ability to self-feed and mark the nursing diagnosis as resolved. This ensures the care plan reflects the current status of the patient's abilities, and care can be adjusted accordingly to focus on other areas the patient may need assistance with.