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': 'The length of Eustachian tube is - \nSelect and explain. \nA. 16mm, B. 24 mm, C. 36mm, D. 40 mm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]