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
The accurate method of diagnosis of gastroesophageal reflux disease (GORD) is - 
Select and explain. 
A. Barium swallow, B. Endoscopy, C. 24 hour pH monitoring, D. Oesophageal manometry
C: 24 hour pH monitoring
Answer: C: 24 hour pH monitoring 
Explanation: None