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: Pharmacology
Which of the following drug can be used in both HIV and Hepatitis B virus? 
Select and explain. 
A. Enfuvirtide, B. Emtricitabine, C. Abacavir, D. Acyclovir
B: Emtricitabine
Answer: B: Emtricitabine 
Explanation: Emtricitabine is a NRTI which has dual action on HIV and Hepatitis B virus.