This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiac and Pericardiac Imaging, Subject name: Radiology
[{'content': 'All of the following are true in chest X ray PA view EXCEPT: \nSelect and explain. \nA. Right ventricle forms the right heart border, B. Left ventricle forms the left heart border, C. Cardiothoracic ratio in adults is normally 50% or less than that, D. Right atrium forms the right heart border', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Right ventricle forms the right heart borderRef: Essential radiology 2nd ed. 122* Right ventricle is not a border forming structure in PA view. However, it forms anterior border in lateral view of Chest X-Ray.', 'role': 'assistant'}]