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
Investigation to be done immediately when an unstable patient comes with blunt abdominal trauma is - 
Select and explain. 
A. USG, B. CT Scan, C. Complete Hemogram, D. Abdominal Xray
A: USG
Answer: A: USG 
Explanation: Ans. is 'a' i.e., USG Stable patient - CT Unstable patient - FAST