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: Radiology
[{'content': 'Restrains development of unexposed silver halide crystals; acts as antifog agents and increases contrast: \nSelect and explain. \nA. Phenidone, B. Sodium hydroxide, C. Bromine containing compound, D. Sodium sulphite', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]