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 most common cause of epistaxis in a 3 years old child - \nSelect and explain. \nA. Nasal polyp, B. Foreign body, C. Upper respiratory catarrh, D. Atrophic rhinitis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Friends – I know some of you must be thinking foreign body as the answer but it is not the most common cause.\nM/C cause of epistaxis in children is idiopathic.\n\n2nd M/C cause of epistaxis in children is', 'role': 'assistant'}]