<prompt> Best investigation for Zenkers diverticulum is:Barium swallowEndoscopyCECTEUS  <response>: Ans. a Barium swallowRef: Sabiston 20th Edition, Page 1020-1022 IOC for Zenkers - Barium swallow IOC for Achalasia - Manometry IOC for Barrets - Endoscopic biopsy 