A Nurse Overhears Another Nurse Say, "That Patient Is Asking

A nurse overhears another nurse say, "That patient is asking for pain medication again. He is constantly on the call bell, always reporting how severe his pain is, and I think he is just drug seeking. I am going to make him wait the full 4 hours before I give this medication again." Which action by the nurse is the most appropriate in this situation?

A) Informing the charge nurse of what was overheard
B) Completing an incident or variance report
C) Ignoring the situation because the patient is not this nurse's responsibility
D) Reminding the nurse, in private, that the sensation of pain is whatever the patient says it is