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
All are true for root canal sealer except: 
Select and explain. 
A. Excessive use of sealer tends to extrusion in periapical areas, B. Sealer mediates immune reaction in perapical region, C. Loss of sealer causes porosity between root filter and tooth surfaces, D. Sealer occupies the space between root filler and tooth surfaces
B: Sealer mediates immune reaction in perapical region
Answer: B: Sealer mediates immune reaction in perapical region 
Explanation: None