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: Pediatrics
Most common cause of pneumonia in children is? 
Select and explain. 
A. RSV, B. Streptococcus pneumoniae, C. Staphylococcus aureus, D. Klebsiella
A: RSV
Answer: A: RSV 
Explanation: "Respiratory syncytial virus (RSV) is the most common cause of pediatric pneumonia"  — OsIci's Paediatrics
"Respiratory viruses are the single most important cause of community-aquired pneumonia in pediatric age group" — Jawetz

Most common cause of pediatric pneumonia → RSV
Most common bacterial cause of pediatric pneumonia → streptococcus pneumoniae