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: Unknown
[{'content': 'Most dangerous sign in LRT1 in children is: \nSelect and explain. \nA. Abdominal breathing, B. Chest retraction, C. Grunting, D. Tachypnea', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Grunting\n\nGrunting is an expiratory sound made by infants as they exhale against a closed glottis.\nIt is an attempt to increase functional residual capacity and lung volume.\nThis is done in order to raise functional residual capacity above the critical closing volume and to avoid alveolar collapse.\nThis physical finding represents impending respiratory failure and should not be overlooked.', 'role': 'assistant'}]