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
[{'content': 'Most common pre cancerous lesion is: \nSelect and explain. \nA. Leukoplakia., B. Erythroplakia., C. Nicotinic stomatitis., D. OSMF.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]