You are answering a USMLE-style medical question. Question: A 54-year-old woman is brought to the physician by her brother for confusion and agitation. She is unable to personally give a history. Her brother says she has a problem with alcohol use and that he found an empty bottle of vodka on the counter at her home. She appears disheveled. Her temperature is 37°C (98.6°F), pulse is 85/min, and blood pressure is 140/95 mm Hg. On mental status examination, she is confused and oriented only to person. She recalls 0 out of 3 words after 5 minutes. She cannot perform serial sevens and is unable to repeat seven digits forward and five in reverse sequence. Neurologic examination shows horizontal nystagmus on lateral gaze. She has difficulty walking without assistance. Laboratory studies show: Hemoglobin 11 g/dL Mean corpuscular volume 110 μm3 Platelet count 280,000/mm3 Which of the following is most appropriate initial treatment for this patient?" Options: A) Intravenous thiamine B) Oral naltrexone C) Intravenous vitamin B12 D) Intravenous glucose " Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.