This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': "65-year-old man presents with anemia, posterior columan dysfunction, and planter extensor. Which of the following is the likely cause \nSelect and explain. \nA. Tabes dorsalis, B. Frederich's ataxia, C. Vitamin B1 deficiency, D. Vitamin B 12 deficiency", 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Vitamin B12 deficiency", 'role': 'assistant'}]