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: Microbiology
Most common Cause of Acute Laryngotraheobronchitis is: 
Select and explain. 
A. Parainfluenza virus, B. H. influenza, C. Influenza virus, D. Measles
A: Parainfluenza virus
Answer: A: Parainfluenza virus 
Explanation: Parainfluenza virus