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: Radiology
[{'content': 'Sea shore sign on USG is see in \nSelect and explain. \nA. Pneumo thorax, B. Normal lung, C. Pleural effusion, D. Pulmonary edema', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sea shore sign - Normal lung.\nLoss of\xa0this pattern (stratosphere sign) - Pneumothorax.', 'role': 'assistant'}]