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
Oesophageal motility disorder are best diagnosed by? 
Select and explain. 
A. Barium studies, B. Endoscopy, C. 24 hour pH monitoring, D. Manometry
B: Endoscopy
Answer: B: Endoscopy 
Explanation: 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.