You are answering a USMLE-style medical question. Question: A 62-year-old man is brought to the emergency department 40 minutes after his wife noticed during breakfast that the left side of his face was drooping. He had difficulty putting on his shirt and shoes before coming to the hospital. He has type 2 diabetes mellitus, hypertension, and hypercholesterolemia. His current medications include metformin, enalapril, and atorvastatin. He has smoked one pack of cigarettes daily for 35 years. He drinks one glass of wine daily. He is alert and oriented to time, place and person. His temperature is 37°C (98.6°F), pulse is 99/min and blood pressure is 170/100 mm Hg. Examination shows equal and reactive pupils. There is drooping of the left side of the face. Muscle strength is decreased in the left upper and lower extremities. Plantar reflex shows an extensor response on the left side. Speech is dysarthric. There is a bruit on the right side of the neck. Fundoscopy shows no abnormalities. A complete blood count, coagulation profile, and serum concentrations of glucose and electrolytes are within the reference range. Which of the following is the most appropriate next step in management? Options: A) MRI of the brain B) Lumbar puncture C) Duplex ultrasonography of the neck D) CT scan of the head Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.