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
Predisposing factors for Alzheimer's disease include all EXCEPT 
Select and explain. 
A. Down's syndrome, B. Low education level, C. Smoking, D. Head injury
C: Smoking
Answer: C: Smoking 
Explanation: (C) Smoking # Risk factors are: Old age, positive family history, head injury, Down's syndrome, low education level, female sex, etc