A nurse at a provider's office receives a telephone call from a client who reports nausea and has unrelieved chest pain after taking a nitroglycerin tablet 5 min ago. Which of the following is an appropriate response by the nurse?

A. Advising the client to come into the office delays emergency care and is unsafe when chest pain persists after nitroglycerin. B. Antacids are not appropriate because the client’s pain is cardiac-related, not gastrointestinal. C. Persistent chest pain after nitroglycerin is a medical emergency and could indicate an acute myocardial infarction. The client should immediately call 911 for emergency services. D. Nitroglycerin tablets may be repeated every 5 min for up to three doses, but since chest pain persists after the first dose, emergency services should be activated rather than waiting longer.