This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdominal Injury, Subject name: Surgery
A case of polytrauma with blunt abdominal injury presents to the casualty. The first investigation to evaluate his abdomen is - 
Select and explain. 
A. USG, B. CT Scan, C. CompleteHemogram, D. Abdominal X-ray
A: USG
Answer: A: USG 
Explanation: Ans. is 'a' i.e., USG o Has been explained in previous sessions