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: Medicine
[{'content': 'Double density sign in Mitral stenosis is a sign of enlargement of \nSelect and explain. \nA. Right Atrium, B. Left Atrium, C. Left Auricle, D. Right Auricle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Answer- B. Left AtriumDouble density is seen on frontal chest radiograph in the presence of left atrial enlargement and occurs when the right side of the left atrium pushes behind the right cardiac shadows indenting the lung and forming its own district sihhouette.', 'role': 'assistant'}]