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: Medicine
Salivary protein which prevents transmission of human immunodeficiency virus via saliva is: 
Select and explain. 
A. Sialoperoxidase, B. Secretory IgA, C. Salivary leukocyte proteinase inhibitor, D. Histidine rich proteins
C: Salivary leukocyte proteinase inhibitor
Answer: C: Salivary leukocyte proteinase inhibitor 
Explanation: Salivary protein which prevents transmission of human immunodeﬁciency virus via  saliva is salivary leukocyte proteinase inhibitor.