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
Initiator in developer solution is 
Select and explain. 
A. Acetic acid, B. Sodium thiosulphate, C. Hydroquinone, D. Potassium bromide
C: Hydroquinone
Answer: C: Hydroquinone 
Explanation: Developer converts exposed silver halide crystals into metallic silver grains. Two developing agents, usually phenidone and hydroquinone, are used in dental radiology.
White and Pharoah, pg-69