Final answer:
The appropriate pain scale for a patient with cognitive impairment is the Behavioral pain scale, which evaluates pain based on observable behaviors rather than relying on the patient's self-reported pain level.
Step-by-step explanation:
For a patient who is cognitively impaired, a pain assessment tool that does not rely on the patient's verbal description or numeric rating scale would be ideal. In this case, the most appropriate pain scale to use is d. Behavioral pain scale.
This type of scale assesses pain based on observable behaviors such as facial expressions, body movements, vocalizations, or changes in interpersonal interactions which are indicators of discomfort or pain.
Unlike numeric or visual scales, it does not require the patient to understand or communicate about their pain in a conventional way, thereby providing a more accurate assessment for those with cognitive impairments.