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: Anaesthesia
[{'content': 'The recommended size of endotracheal tube for 1 year old child is \nSelect and explain. \nA. 2.5, B. 3, C. 4, D. 5', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Tube diameter in mm\n= Age in years/4 + 4\n= 1/4 + 4\n= 17/4\n= 4.2', 'role': 'assistant'}]