This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
[{'content': 'Systemic acyclovir in herpes zoster is useful: \nSelect and explain. \nA. When staed immediately after the onset of rash, B. For post-herpetic neuralgia, C. For ocular lesions only, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. When staed immediately after the onset of rash', 'role': 'assistant'}]