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 these is a qualitative test for bacteria: 
Select and explain. 
A. Snyder test, B. Allen's test, C. Dentocult test, D. Salivary reductase test
D: Salivary reductase test
Answer: D: Salivary reductase test 
Explanation: None