This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Pediatrics
[{'content': 'True about Chest radiographs of children with foreign body aspiration is: \nSelect and explain. \nA. Always abnormal, B. May show hyperinflation of one lung field, C. Always show antibody, D. Will always present with pneumothorax', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. May show Hyperinflation of one lung field.The hallmark of an aspirated foreign body is a lung volume that does not change during the respiratory cycle. Due to the check valve mechanism, where air enters the bronchus around the foreign body but cannot exit, the affected lung will usually appear overinflated and hyperlucent, with concomitant rib flaring and a depressed ipsilateral hemidiaphragm. The chest X-ray will be normal in 35% (range 30-40%) of patients, unilateral emphysema or atelectasis are the most common findings; only uncommonly will a radio-opaque foreign body be demonstrated.', 'role': 'assistant'}]