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': '55-year-old male with a recurrent episode of fall, rigidity and autonomic insufficiency - \nSelect and explain. \nA. Railey day syndrome, B. Shy-dragger syndrome, C. Basal ganglionic lesion, D. Parkinsonism', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]