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
A 2 years male boy presenting with sudden severe dyspnoea, most common cause is - 
Select and explain. 
A. Foreign body, B. Bronchiolitis, C. Asthmatic Attack, D. None
A: Foreign body
Answer: A: Foreign body 
Explanation: None