A 45-year-old man with a history of orthotopic lung transplantation 3 years ago presents to the hospital with a 2-week history of progressive dyspnea, fever, and nonproductive cough. Chest CT shows diffuse bilateral ground-glass opacities. Transbronchial biopsy reveals large cells with intranuclear inclusions surrounded by a clear halo ("owl's eye" appearance). He is started on ganciclovir 5 mg/kg IV twice daily, but after 10 days of therapy shows clinical deterioration with worsening hypoxemia and rising viral load on PCR. A resistance mutation in viral DNA polymerase is identified. He is switched to an alternative antiviral agent and demonstrates clinical improvement within 48 hours. Which of the following best describes the mechanism of action of the drug used for successful treatment?

1. A)Inhibits viral DNA polymerase after being phosphorylated by viral thymidine kinase
2. B)Inhibits viral DNA polymerase without requiring viral or cellular kinase activationGABARITO
3. C)Inhibits viral reverse transcriptase by competing with nucleotide substrates
4. D)Inhibits viral integrase by preventing strand transfer reactions
5. E)Inhibits viral protease leading to production of immature non-infectious particles