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 is a prodrug of Penciclovir? 
Select and explain. 
A. Valacyclovir, B. Valganciclovir, C. Cidofovir, D. Famciclovir
D: Famciclovir
Answer: D: Famciclovir 
Explanation: Famciclovir is the prodrug of penciclovir which is a Guanosine analogue used against herpes.