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: Unknown
[{'content': 'A 29 year male complains of pain in the flank that radiates from the loin to the groin region. The first investigation to be done is - \nSelect and explain. \nA. CECT, B. Plain CT Scan, C. USG abdomen, D. Xray Abdomen', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. is C. First investigation is USG>Xray Abdomen IOC is CT Gold standard investigation for renal calculi: Non contrast CT scan', 'role': 'assistant'}]