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
The bacteria of oral flora which plays least role in periodontitis is: 
Select and explain. 
A. Actinomyces, B. Actinomycetam comitans, C. Spirocheates, D. Bacteriodes
A: Actinomyces
Answer: A: Actinomyces 
Explanation: None