This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Viral Drugs, Subject name: Pharmacology
Drug effective against both hepatitis B as well as HIV is 
Select and explain. 
A. Acyclovir, B. Foscarnet, C. Lamivudine, D. Cidofovir
C: Lamivudine
Answer: C: Lamivudine 
Explanation: Lamivudine is NI used in both HIV and hepatitis B (low dose).Lamivudine is effective in chronic hepatitis B;this is due to longer intracellular t1/2 of lamivudine in HBV infected cells than in HIV infected cells. Acyclovir - effective against HSV-1>HSV-2>VZV=EBV. Foscarnet -effective against H.simplex,CMV,other herpes group viruses and HIV. Cidovofir- effective against HSV,CMV,pox and adenoviruses.