This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Medicine
[{'content': 'Esophageal motility disorder is best diagnosed is? \nSelect and explain. \nA. Barium studies, B. Esophagoscopy, C. 24 hour pH monitoring, D. Manometry', 'role': 'user'}, {'content': 'Answer: D \nExplanation: <p>Davidson&;s principles and practice of medicine 22nd edition. *Manometry confirms the high pressure non relaxing oesophageal sphincter with poor contractility of the oesophageal body.</p>', 'role': 'assistant'}]