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: Anatomy
Torus aoicus is an impression in the cavity of: 
Select and explain. 
A. Right atrium, B. Left atrium, C. Right ventricle, D. Left ventricle
A: Right atrium
Answer: A: Right atrium 
Explanation: Torus aoicus is a bulge in the right atrial wall anterosuperiorly above the membranous septum. It is superior to the coronary sinus and anterior to the fossa ovalis. It represents the deeper and anterior surface of the posterior sinus and cusp of the aoic valve. Ref: Greys Anatomy, 38th Edition, Page 1480