Acyclovir valacyclovir famciclovir

Which of the following best describes the conversion process of acyclovir to acyclovir triphosphate?

1: Acyclovir is converted directly to acyclovir triphosphate via cellular enzymes.
2: Acyclovir is spontaneously converted to acyclovir triphosphate in the presence of ATP.
3: Acyclovir is first converted into acyclovir monophosphate via virus-encoded thymidine kinase, then cellular enzymes perform the subsequent phosphorylation steps.
4: Acyclovir is first converted into acyclovir monophosphate via cellular enzymes, then virus-encoded thymidine kinase performs the additional phosphorylation steps.