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
[{'content': 'Regarding Hepatitis-B, which is true: \nSelect and explain. \nA. It is a RNA virus, B. Incubation period is 2-4 weeks, C. HbeAg denotes maximum protection, D. HbsAg may be present in saliva', 'role': 'user'}, {'content': 'Answer: D \nExplanation: HbsAg may be present in saliva', 'role': 'assistant'}]