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': 'Which of the following represents the surface marking of the aoic valve ? \nSelect and explain. \nA. Sternal end of left 3rd costal cailage, B. Sternal end of right 3rd costal cailage, C. Besides the sternum in left 3rd intercostal space, D. Besides the sternum in right 3rd intercostals space', 'role': 'user'}, {'content': "Answer: A \nExplanation: Surface marking of aoic valve is slightly oblique line,2.5 cm long behind left half of sternum at the level of lower border of left 3rd coastal cailage. BD CHAURASIA'S HUMAN ANATOMY.VOLUME1. 6TH EDITION.PAGE NO 291. TABLE NO 21.1 surface marking of cardiac valves", 'role': 'assistant'}]