This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2019, Subject name: Surgery
A 25 years old college student met with road traffic accident and is admitted in casualty. He has marked abdominal distension, pulse rate of 140/minute and a BP of 80/50 mm Hg. The most appropriate initial investigation would be:- 
Select and explain. 
A. Abdominal paracentesis, B. CT abdomen, C. Plain x- ray of abdomen, D. FAST scan
D: FAST scan
Answer: D: FAST scan 
Explanation: Any patient of blunt trauma abdomen - first investigation done is FAST (stable / unstable) After FAST: - If patient unstable - exploratory laparotomy - If patient stable - CECT