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
Which of the following microorganisms are commonly present in large percentage of root canal treated teeth that present with persistent periradicular lesions indicative of failed treatment? 
Select and explain. 
A. Porphyromonasgingivalis, B. Tannerella forsythia, C. Dialisterinvisus, D. Enterococcus faecalis
D: Enterococcus faecalis
Answer: D: Enterococcus faecalis 
Explanation: None