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: Pathology
Most common pre cancerous lesion is: 
Select and explain. 
A. Leukoplakia., B. Erythroplakia., C. Nicotinic stomatitis., D. OSMF.
A: Leukoplakia.
Answer: A: Leukoplakia. 
Explanation: None