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: Psychiatry
Most common cause dementia in adult: 
Select and explain. 
A. Alzheimer's, B. Multiinfarct, C. Pick' disease, D. Metabolic cause
A: Alzheimer's
Answer: A: Alzheimer's 
Explanation: A i.e. Alzheimer's