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: Microbiology
Regarding Hepatitis-B, which is true: 
Select and explain. 
A. It is a RNA virus, B. Incubation period is 2-4 weeks, C. HbeAg denotes maximum protection, D. HbsAg may be present in saliva
D: HbsAg may be present in saliva
Answer: D: HbsAg may be present in saliva 
Explanation: HbsAg may be present in saliva