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': 'The most common presentation of radiation carditis is: \nSelect and explain. \nA. Pericardial effusion, B. Atheromatous plaques, C. Myocardial fibrosis, D. Pyogenic pericarditis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Pericardial effusion', 'role': 'assistant'}]