This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oesophagus, Subject name: Surgery
Best investigation for Zenker's diverticulum is: 
Select and explain. 
A. Barium swallow, B. Endoscopy, C. CECT, D. EUS
A: Barium swallow
Answer: A: Barium swallow 
Explanation: Ans. (a) Barium swallowRef: Sabiston 20th Edition, Page 1020-1022* IOC for Zenker's - Barium swallow* IOC for Achalasia - Manometry* IOC for Barret's - Endoscopic biopsy