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': 'Oreo cookie sign is a radiological finding of \nSelect and explain. \nA. Aberrant subclavian artery, B. Pericardial effusion, C. Left atrium enlargement, D. Endomyocardial fibrosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Oreo - cookie sign - radioopaque pericardial fluid is borderd on either side by echo - dense pericardial fat.', 'role': 'assistant'}]