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: Surgery
[{'content': 'A patient present with dysphagia of 4 weeks duration. Now he is able to swallow liquid food only. Which of the following is the one investigation to be done - \nSelect and explain. \nA. Barium studies are the best in this case, B. Upper GI endoscopy is to be done, C. CT scan is needed, D. Esophageal manometry', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]