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
A 45-year-old man presents with history of frequent falls. He has difficulty in looking down also. What is the most probable diagnosis : 
Select and explain. 
A. Normal pressure hydrocephalus, B. Parkinson's disease, C. Alzheimer's disease, D. Progressive supranuclear palsy
D: Progressive supranuclear palsy
Answer: D: Progressive supranuclear palsy 
Explanation: Answer is D (Progressive supranuclear palsy):