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. drug regimen as an effective method of pain control would be the client in the postoperative stage with occasional pain.
P.R.N. stands for pro re nata, which means 'as needed' in Latin. In this case, it means that the medication is given as needed when the client is experiencing pain. So, the client who has occasional pain would benefit from this type of regimen as they can take the medication when they need it.