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: Dental
[{'content': 'In a 3x3 table, the number of degrees of freedom is: \nSelect and explain. \nA. 4, B. 9, C. 3, D. 81', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]