This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
[{'content': "Predisposing factors for Alzheimer's disease include all EXCEPT \nSelect and explain. \nA. Down's syndrome, B. Low education level, C. Smoking, D. Head injury", 'role': 'user'}, {'content': "Answer: C \nExplanation: (C) Smoking # Risk factors are: Old age, positive family history, head injury, Down's syndrome, low education level, female sex, etc", 'role': 'assistant'}]