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
Gastroesophageal reflux disease confirmed by: 
Select and explain. 
A. Manometry, B. Upper gastrointestinal endoscopy, C. 24 hr pH monitoring, D. Barium meal
C: 24 hr pH monitoring
Answer: C: 24 hr pH monitoring 
Explanation: Ans C.24 hr pH monitoringExplanationInvestigation for gastroesophageal reflux disease (GERD)RadiographyBarium radiology is, however, inaccurate in the diagnosis of gastroesophageal reflux, unless reflux is gross.CT to differentiate from neoplasms EndoscopyUpper gastrointestinal endoscopy is most appropriate examination if GERD is associated with dysphasiaEsophageal manometryPressure of lower esophageal shincture is also required24 hour pH and combined pH impedance monitoringGold standard for diagnosis