Final answer:
The best way to evaluate the repositioning intervention for a pressure ulcer is by observing changes in skin integrity and the ulcer's healing. This method directly relates to the effectiveness of the intervention.
Step-by-step explanation:
The best evaluation method for the intervention of repositioning an immobile client with a pressure ulcer every 2 hours is C. Observing the client's skin integrity and the healing progress of the pressure ulcer. This direct approach allows the nurse to determine if the repositioning schedule is effective by monitoring changes in the ulcer's appearance and size. Assessing the client's pain level and monitoring vital signs, while important, do not provide specific information about the effectiveness of the ulcer's treatment. Evaluating the client's ability to perform activities of daily living independently is also crucial for overall care but does not directly address the healing of the pressure ulcer.