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
Investigation of choice in peptic ulcer perforation is ? 
Select and explain. 
A. USG, B. X-Ray abdomen, C. Paracentesis, D. CT scan
B: X-Ray abdomen
Answer: B: X-Ray abdomen 
Explanation: Ans. is 'b' i.e., X-ray abdomen