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': 'Radiological feature of Mitral stenosis is are \nSelect and explain. \nA. Double contour of right hea border, B. Straightening of left hea border, C. Splaying of carinal angle, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A, B, C i.e. Double contour of right hea border, Straightening of left hea border, Splaying of carinal angle', 'role': 'assistant'}]