This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
[{'content': 'Best test to diagnose gastroesophageal reflux disease and quantity acid output is \nSelect and explain. \nA. Esohagogram, B. Endoscopy, C. Manometry, D. 24 Hr pH monitoring', 'role': 'user'}, {'content': 'Answer: D \nExplanation: .for GERD, THE INVESTIGATIONS can be, *24 hours oesophageal pH monitoring is regarded as the gold standard.PPI should be stopped for 3 weeks prior to pH monitoring. *barium study in head down position. *endoscopy to exclude other diseases. *oesophagal manometry to assess the state of lower oesophagal sphincter. Ref: SRB&;s manual of surgery,5th ed, pg no 792', 'role': 'assistant'}]