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
[{'content': 'All are risk factors of squamous cell carcinoma except \nSelect and explain. \nA. Ultraviolet radiation, B. Tar, C. Tobacco, D. HPV 18', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]