While Counting the Apical Pulse in a 16-Year-Old Patient,the Nurse

While counting the apical pulse in a 16-year-old patient,the nurse notes an irregular rhythm.His rate speeds up on inspiration and slows on expiration.What would the nurse do next?

A) Talk to the patient about his intake of caffeine.
B) Do an electrocardiogram after the examination.
C) No further action is needed because this is normal.
D) Refer the patient to a cardiologist for further testing.