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
[{'content': 'Which of the following is the gold standard test for Laryngopharyngeal Reflux? \nSelect and explain. \nA. 24 hour double probe pH monitoring, B. Esophageal biopsy, C. Abnormal esophageal radiography (BariumSwallow), D. Esophageal motility studies', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Currently, the Gold standard test for Laryngopharyngeal Reflux is 24 hour double probe pH monitoring. An arbitrary threshold of pH=4 is used to diagnose reflux whether at the esophageal probe (5 cm above the lower esophageal sphincter) for gastroesophageal reflux or at the pharyngeal probe (2 cm above the upper esophageal sphincter) for laryngopharyngeal reflux (LPR).', 'role': 'assistant'}]