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': 'The most reliable single histologic criterion for diagnosis of oral squamous cell carcinoma is: \nSelect and explain. \nA. Invasion, B. Degeneration, C. Pleomorphism, D. Encapsulation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]