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: ENT
[{'content': 'Bifurcation of trachea takes place at - \nSelect and explain. \nA. T4 - T5, B. C6 -C7, C. C3 - C4, D. T10 - T11', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]