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
Which of the following is not a risk factor for oropharyngeal carcinoma? 
Select and explain. 
A. Chronic hypertrophic candidiasis, B. Oral submucous fibrosis, C. Erythroplakia, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: Leukoplakia.
Erythroplakia.
Submucous fibrosis.
Lichen planus
Laryngeal keratosis
Actinic cheliosis
Smooth,red tonque of plummer - vinson syndrome.