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: Pathology
[{'content': "Irreversible dementia is caused due to: \nSelect and explain. \nA. Subarachnoid hemorrhage, B. Wilson's disease, C. Normal pressure hydrocephalus (NPH), D. Vascular dementia", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Vascular dementia is a cause of progressive dementia due to impaired blood supply to the brain.', 'role': 'assistant'}]