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: Surgery
[{'content': 'Dennis stability concept is based on which of the following \nSelect and explain. \nA. 2 columns, B. 3 columns, C. 4 columns, D. 5 columns', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. 3 columns', 'role': 'assistant'}]