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: Surgery
[{'content': 'Investigation of choice for diagnosing intra abdominal bleeding in an unstable patient: September 2007 \nSelect and explain. \nA. CT scan omit, B. MRI scan, C. USG, D. Diagnostic peritoneal lavage', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C: USG', 'role': 'assistant'}]