This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Surfaces and Grooves, Subject name: Anatomy
Which of the following represents the surface marking of the aoic valve: 
Select and explain. 
A. Sternal end of the left 3rd costal cailage, B. Sternal end of the right 3rd costal cailage, C. Behind the sternum in left 3rd intercostal space, D. Behind the sternum in right 3rd intercostal space
C: Behind the sternum in left 3rd intercostal space
Answer: C: Behind the sternum in left 3rd intercostal space 
Explanation: Aoic valve is represented by an oblique line (2.5 cm) running inferolaterally and to the right from the medial end of the left third intercostal space (and behind the corresponding region of the sternum).