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
Best diagnostic aid in blunt trauma abdomen is - 
Select and explain. 
A. CT scan, B. 4 quadrant aspiration, C. Peioneal lavage, D. Ultrasound
D: Ultrasound
Answer: D: Ultrasound 
Explanation: Ans. is 'd' i.e., Ultrasound