This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Viral Drugs, Subject name: Pharmacology
[{'content': 'Ganciclovir is preferred over acyclovir in the following condition: \nSelect and explain. \nA. Herpes simplex keratitis, B. Herpes zoster, C. Chickenpox, D. Cytomegalovirus retinitis in AIDS patients', 'role': 'user'}, {'content': 'Answer: D \nExplanation: * Ganciclovir is the drug of choice for CMV infections. * Acyclovir is highly effective against Herpes simplex and Varicella zoster (chicken pox and herpes zoster) but it has very little activity against CMV.', 'role': 'assistant'}]