This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Surgery
[{'content': 'Water soluble contrast made up of \nSelect and explain. \nA. Iodine, B. Barium, C. Calcium, D. Bromine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: There are two types of Water soluble contrast:- Ref:- Surgery Sixer 3rd Edition; Pg num:- 327', 'role': 'assistant'}]