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: Surgery
Not a carcinogenic for cancer of Head & Neck - 
Select and explain. 
A. Alcohol, B. Smoking, C. Tobacco, D. Unflourinated water
D: Unflourinated water
Answer: D: Unflourinated water 
Explanation: None