This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
[{'content': 'Surface marking of the mitral valve is \nSelect and explain. \nA. Behind sternal end of left 4th costal cailage, B. Behind sternal end of right 4th costal cailage, C. Left 4th intercostal space in the midclavicular line, D. Left 3rd intercostal space in the midclavicular line', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Surface marking of mitral value is an oblique line 3 cm behind the left half of sternum opposite left 4th coastal cailage. <img src=" /> BD CHAURASIA\'S HUMAN ANATOMY.VOLUME 1.6TH EDITION.PAGE NO 291.TABLE 21.1:SURAFACE MARKING OF CARDIAC VALVE', 'role': 'assistant'}]