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
In the Dentocult lactobacilli test, low caries activity is determined by: 
Select and explain. 
A. ＞10,000 C.F.U, B. ＜1000 C.F.U, C. ＜1,000,000 C.F.U, D. ＜10,000 C.F.U
B: ＜1000 C.F.U
Answer: B: ＜1000 C.F.U 
Explanation: None