You are answering a USMLE-style medical question. Question: An 80-year-old man is brought to the emergency department because of fatigue and lightheadedness. He does not have chest pain, palpitations, or difficulty breathing. He has a history of hyperlipidemia, type 2 diabetes mellitus, hypertension, osteoarthritis, and asthma. Current medications include simvastatin, metformin, lisinopril, albuterol, and ibuprofen. His pulse is 48/min and blood pressure is 89/50 mm Hg. He responds slowly to questions but is oriented to person, place, and time. Examination shows dry mucous membranes. His lungs are clear to auscultation and bowel sounds are positive with no pulsatile masses or bruits. Pedal pulses are nonpalpable, distal extremities are cold, and capillary refill time is 4 seconds. An ECG shows left axis deviation, a Q wave in lead III, a constant PR interval of 0.15 seconds with every third P wave that is nonconducted, and a QRS interval of .09 seconds. Which of the following is the most appropriate next step in management? Options: A) Dobutamine B) Norepinephrine C) Cardiac pacing D) Epinephrine Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.