This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Torus aoicus is an impression in the cavity of \nSelect and explain. \nA. Right atrium, B. Right ventricle, C. Left ventricle, D. Left atrium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Torus aoicus (aoic mound) is the prominent region of the right atrial septum, which marks the projection of the non-coronary aoic sinus into the right atrial wall. The bulge is superior to the coronary sinus and anterior to the fossa ovalis.', 'role': 'assistant'}]