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: Pediatrics
The gold standard investigation for Gastro-esophageal reflux disease is 
Select and explain. 
A. Endoscopy, B. 24 hour ph recording, C. Oesophageal manometry, D. None of the above
B: 24 hour ph recording
Answer: B: 24 hour ph recording 
Explanation: 24 hour ph monitoring of distal esophagus provides quantitative sensitive documentation of acidic reflux episodes.