This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamentals in Radiology, Subject name: Radiology
[{'content': 'The active ingredient of X-ray film is - \nSelect and explain. \nA. Silver chloride, B. Silver bromide, C. Silver nitrate, D. Gold chloride', 'role': 'user'}, {'content': 'Answer: B \nExplanation: An X ray film consists of polyster base ,emulsion,and crystals of Silver Halide.The silver bromide crystals are spread over emulsion that is applied on a polyester base.', 'role': 'assistant'}]