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': 'Most important investigation for pericardial effusion – \nSelect and explain. \nA. Cardiac catheterization, B. USG, C. Echocardiography, D. X-ray chest', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 2 D-echo is the investigation of choice for pericardial effusion.', 'role': 'assistant'}]