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
All of the following casues subcortical dementia except- 
Select and explain. 
A. Alzhimer's disease, B. Parkinsonism, C. HIV encephalopathy, D. Progressive supra nuclear palsy
A: Alzhimer's disease
Answer: A: Alzhimer's disease 
Explanation: None