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': 'Definitive diagnosis of oral cancer is made by \nSelect and explain. \nA. Complete radiographic survey, B. Biopsy, C. Exfoliative cytology, D. Pantograph', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]