Which explanation best accounts for the selective activity of acyclovir against herpes viruses but not most host cells?

Acyclovir must be converted into a protein by viral proteases which then embeds in the viral envelope preventing the virus from entering neighboring cells; therefore it only acts where viral proteases are present.

Acyclovir is preferentially phosphorylated by the viral thymidine kinase encoded by herpes, producing the active triphosphate that viral DNA polymerase incorporates, causing chain termination.

Acyclovir passively diffuses only into infected cells because herpes virions alter membrane lipid composition so the drug is trapped solely within infected cells and excluded from uninfected host cells.

Acyclovir binds directly to host topoisomerase II only when viral proteins are present, creating DNA breaks that exclusively affect viral genomes while leaving host chromosomes intact.