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
Most root canals that have not been instrumented are too narrow to be reached effectively by 
Select and explain. 
A. Microbes, B. Disinfectants, C. Gutta percha, D. None of the above
B: Disinfectants
Answer: B: Disinfectants 
Explanation: None