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: Dental
Radio-opacity in composite is due to presence of 
Select and explain. 
A. Strontium, B. Fluorides, C. Silica, D. BisGMA
A: Strontium
Answer: A: Strontium 
Explanation: None