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 dangerous sign in lower respiratory tract infection in children is __________ 
Select and explain. 
A. Chest retraction, B. Tachypnea, C. Grunting, D. Abdominal breathing
C: Grunting
Answer: C: Grunting 
Explanation: Grunting ⇒ 
Expirating against partially closed glottis.
It is an attemp to maintain positive airway pressure during expiration.