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: ENT
Gold standard test for diagnosis of laryngopharyngeal reflux is - 
Select and explain. 
A. 24 hr double probe pH monitoring, B. Flexible endoscope, C. Barium swallow, D. Laryngoscopy
A: 24 hr double probe pH monitoring
Answer: A: 24 hr double probe pH monitoring 
Explanation: None