Final answer:
The client that would benefit from a p.r.n. drug regimen as an effective method of pain control would be the client in the postoperative stage with occasional pain.
Step-by-step explanation:
The client that would benefit from a p.r.n. (as needed) drug regimen as an effective method of pain control would be the client in the postoperative stage with occasional pain. This is because after a surgical procedure, the client may experience intermittent pain that can be managed effectively with medication that is taken as needed.
On the other hand, a client experiencing acute pain or chronic pain would require a more consistent and scheduled drug regimen to control their pain on a regular basis.