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 young patient presents with history of dysphagia more to liquid than solids. The first investigation you will do is - \nSelect and explain. \nA. Barium Swallow, B. Esophagoscopy, C. Ultrasound of the chest, D. C.T. Scan of the chest', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]