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 is not present in saliva: 
Select and explain. 
A. Lysozyme, B. Phosphate, C. Bicarbonate, D. Trypsin
D: Trypsin
Answer: D: Trypsin 
Explanation: None