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
All are precancerous lesions of oral cavity except 
Select and explain. 
A. Leukoplakia, B. Erythroplakia, C. Diffuse oral submucous fibrosis, D. Diffuse aphthous ulcers
D: Diffuse aphthous ulcers
Answer: D: Diffuse aphthous ulcers 
Explanation: Premalignant Lesions - Leukoplakia Erythroplakia Oral submucous fibrosis Melanosis and mucosal hyperpigmentation Ref: Dhingra; Textbook of Ear, Nose and Throat; 7th Edition; Page 253