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
Reversible cause of dementia -a) Post encephalitisb) Multi infarctc) Hydrocephalusd) Senile dementia 
Select and explain. 
A. a, B. bc, C. ad, D. ac
D: ac
Answer: D: ac 
Explanation: Chronic meningoencephalitis and hydrocephalus are reversible causes of dementia.