Acyclovir Is Selective and Low in Toxicity, Causing Little Harm

Acyclovir is selective and low in toxicity, causing little harm to uninfected cells, because

A) only a virally encoded enzyme can convert the medication into its active form (from nucleoside analog to nucleotide analog) . 
B) only a virally encoded enzyme can convert the medication into its active form (from nucleotide analog to nucleoside analog) . 
C) viral DNA is structurally very different from cellular DNA.
D) host cells have the ability to repair the damage caused by nucleotide analogs.
E) host cells have an enzyme that prevents the conversion of the medication into its active form.