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 Zenker's diveiculum is: 
Select and explain. 
A. CECT, B. Endoscopy, C. Esophageal manometry, D. Barium Swallow
D: Barium Swallow
Answer: D: Barium Swallow 
Explanation: Ans is `d' i.e. Barium Swallow "Once suspected, the diagnosis is established by a barium swallow. Endoscopy is usually difficult in the presence of a cricopharyngeal diveiculum, and potentially dangerous, owing to obstruction of the true esophageal lumen by the diveiculum and the attendant risk of \\diveicular peiforation."- Schwaz