This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oral cavity & Oesophagus, Subject name: ENT
Which of the following is not a premalignant condition oral cancer? 
Select and explain. 
A. Leukoplakia, B. Erythroplakia, C. Oral submucous fibrosis, D. Systemic Sclerosis
D: Systemic Sclerosis
Answer: D: Systemic Sclerosis 
Explanation: Lesions with an increased risk of malignancy on oral cancerPremalignant condition:- Leukoplakia, Erythroplakia, speckled erythroplakia, chronic hyperplastic candidiasisConditions increasing risk:- Oral submucous fibrosis, syphilitics glossitis, sideropenic dysphagia (Peterson Kelly syndrome)The risk is doubtful:- Oral lichen planus, DLE, Dyskeratosis congenital.Ref: PL Dhingra, Diseases of Ear, Nose & Throat, 7th edition, pg no. 253