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: Medicine
[{'content': 'Oesophageal motility disorder are best diagnosed by? \nSelect and explain. \nA. Barium studies, B. Endoscopy, C. 24 hour pH monitoring, D. Manometry', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Answer is B (Endoscopy): Dysphagia for solids alone suggests a probable mechanical cause for dysphagia such as carcinoma, stricture or esophageal web. The investigation of choice for such cases is Endoscopy.', 'role': 'assistant'}]