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: Unknown
Trisodium phosphonoformate (foscarnet) is a po¬tent antiviral agent for treating herpes simplex infec¬tions. It works by affecting 
Select and explain. 
A. The viral RNA polymerase, B. The viral DNA polymerase, C. The viral reverse transcriptase, D. The host-cellular DNA polymerase
B: The viral DNA polymerase
Answer: B: The viral DNA polymerase 
Explanation: Trisodium phosphonoformate (foscarnet) inhibits herpes simplex virus (HSV) replication. Foscarnet is a potent inhibitor of HSV-induced DNA polymerase, and has little effect on known cellular DNA polymer­ases. Herpesvirus mutants resistant to the drug arise easily.
To a lesser extent, foscarnet also appears to inhibit the polymerase of hepatitis B virus and retroviruses.
Combinations of antivirals, including foscarnet, are currently prescribed to increase the clinical usefulness of the drugs.