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
Hummingbird sign in brain MRI is seen in - 
Select and explain. 
A. Multiple sclerosis, B. Progressive supranuclear palsy, C. Parkinson's disease, D. Alzheimer disease
B: Progressive supranuclear palsy
Answer: B: Progressive supranuclear palsy 
Explanation: Ans. is 'b' ie., Progressive supranuclear palsy * Hummingbird sign on brain MRI is a radiological sign of progressive supranuclear palsy.