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: Radiology
[{'content': 'All are seen on right side of cardiac shadow in X-Ray chest PA view except \nSelect and explain. \nA. Superior venacava, B. Rt. atrium, C. Ascending Aoa, D. Inferior venacava', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Ascending aoa', 'role': 'assistant'}]