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': 'True about Eustachian tube is / are -a) Size is 3.75 cmb) Cartilagenous 1/3 & 2/3rd bonyc) Opens during swallowingd) Nasopharyngeal opening is narroweste) Tensor palati helps to open it \nSelect and explain. \nA. acd, B. bde, C. ace, D. ade', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]