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': 'Earliest sign of OSMF: \nSelect and explain. \nA. Burning sensation, B. Blanching, C. Restricted mouth opening., D. Circum oral bands.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Earliest complaint : burning sensation\nEarliest sign : blanching', 'role': 'assistant'}]