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
The active ingredient of X-ray film is - 
Select and explain. 
A. Silver chloride, B. Silver bromide, C. Silver nitrate, D. Gold chloride
B: Silver bromide
Answer: B: Silver bromide 
Explanation: 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.