This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bronchiectasis, Subject name: Medicine
The most common cause of bronchiolitis is: 
Select and explain. 
A. Respiratory syncytial virus, B. Adenovirus, C. Herpes virus, D. Influenza virus
A: Respiratory syncytial virus
Answer: A: Respiratory syncytial virus 
Explanation: M/C organism causing Bronchiolitis is RSV Other organisms are :- Influenza virus Parainfluenza virus Human metapneumovirus Coronavirus Adenovius Rhinovirus Palivizumab injection is used to prevent serious lung infection in children and babies caused by respiratory syncytial virus (RSV).