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
Which of the following reduces the development of unexposed Ag halide crystals, and also acts as antifog agent? 
Select and explain. 
A. Phenidone, B. Potassium hydroxide, C. Sodium sulfite, D. Sodium bromide
D: Sodium bromide
Answer: D: Sodium bromide 
Explanation: None