This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Radiology
[{'content': "Hummingbird sign in brain MRI is seen in - \nSelect and explain. \nA. Multiple sclerosis, B. Progressive supranuclear palsy, C. Parkinson's disease, D. Alzheimer disease", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' ie., Progressive supranuclear palsy * Hummingbird sign on brain MRI is a radiological sign of progressive supranuclear palsy.", 'role': 'assistant'}]