This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Radiology, Subject name: Radiology
[{'content': 'Spinnaker sign is a feature of \nSelect and explain. \nA. Pleural effusion, B. Pneumothorax, C. Pneumomediastinum, D. Fracture of bronchus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Thymic sail sign is the normal appearance of thymic shadow abutting the Hea shadow seen on Chest X ray of a normal Infant Spinnaker sail sign is the lifting of the Thymic shadow with the lucency of air between Thymus and Hea in cases Of Pneumomediastinum thymus sail sign- normal spinnaker sign', 'role': 'assistant'}]