This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hea Sounds, Subject name: Medicine
[{'content': 'In Mitral Stenosis ,double atrial shadow is due to enlargement of ? \nSelect and explain. \nA. Right atrium, B. Left atrium, C. Both atria, D. Left auricle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Double-density sign/Double atrial shadow Seen on frontal chest radiograph in the presence of left atrial enlargement Occurs when the right side of the left atrium pushes behind the right cardiac shadow, indenting the adjacent lung and forming its own distinct silhouette.', 'role': 'assistant'}]