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 for Pseudo - obstruction 
Select and explain. 
A. Barium enema, B. CECT, C. Water soluble contrast enema, D. Colonoscopy
C: Water soluble contrast enema
Answer: C: Water soluble contrast enema 
Explanation: None