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
The most common cause of epistaxis in a 3 years old child - 
Select and explain. 
A. Nasal polyp, B. Foreign body, C. Upper respiratory catarrh, D. Atrophic rhinitis
C: Upper respiratory catarrh
Answer: C: Upper respiratory catarrh 
Explanation: Friends – I know some of you must be thinking foreign body as the answer but it is not the most common cause.
M/C cause of epistaxis in children is idiopathic.

2nd M/C cause of epistaxis in children is