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
[{'content': 'Investigation to diagnose the Laryngo pharyngeal reflux \nSelect and explain. \nA. Esophageal pH monitoring, B. Dual Probe Impedance pH monitoring, C. Barium Esophagogram, D. Scintigraphy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Dual Probe Impedance pH MonitoringRef: Shackelford Page 222/8th Edition* pH monitoring at the level of Pharynx is not helpful because the acid refluxed is neutralized by the Pharyngeal secretions.* Hence a Dual (Bifurcated) catheter measuring both pH and Impedance is used across Upper esophageal sphincter, thereby permitting detection of Pharyngeal reflux', 'role': 'assistant'}]