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
Which is the baseline investigation in the case of an acute abdomen in this high - tech era - 
Select and explain. 
A. Abdomen CT, B. Abdomen X - Ray, C. USG, D. Colonoscopy
B: Abdomen X - Ray
Answer: B: Abdomen X - Ray 
Explanation: Ans. is 'b' i.e., Abdomen X-Ray