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: Pathology
Bacteria responsible for initiation of caries is: 
Select and explain. 
A. Actinomyces, B. Strep. mutans, C. Lactobacillus, D. Strep. viridans
B: Strep. mutans
Answer: B: Strep. mutans 
Explanation: None