This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Surgery
All are risk factors of squamous cell carcinoma except 
Select and explain. 
A. Ultraviolet radiation, B. Tar, C. Tobacco, D. HPV 18
D: HPV 18
Answer: D: HPV 18 
Explanation: Ultraviolet radiation, chronic inflammation, and chemical carcinogens (arsenicals, tar) and infection with HPV 5 and 16.There is also evidence that current and previous tobacco use doubles the relative risk of SCC.Ref: Bailey and Love, 27e, page: 606