The Nurse Inquires of a Postoperative Client as to the Need

The nurse inquires of a postoperative client as to the need for pain medication.The client denies the need then but 30 minutes later reports,"I am really in a lot of pain.Can you bring me my pain pill now?" The nurse recognizes that the most immediate need for client education is related to explaining that:

A) His oral medication will take approximately 30 minutes to affect his pain
B) There may be a need to administer his pain medication via the intravenous route
C) Pain medication is more effective if blood levels are maintained at a constant level
D) His pain will be more effectively managed if he reports a need for pain medication while the pain is still tolerable