This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'A term baby girl has two episodes of bile-stained emesis at 24 hours after bih. There is a history of excessive amniotic fluid volume. The most appropriate diagnostic test is? NOT RELATED - MEDICINE \nSelect and explain. \nA. Blood culture, B. Barium swallow and Gastrointestinal X rays, C. CT scan of head, D. Neurosonogram', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]