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': 'The nerve which is most frequently involved in herpes zoster ophthalmicus is: \nSelect and explain. \nA. Frontal nerve, B. Nasociliary nerve, C. Lacrimal nerve, D. Facial nerve', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Frontal nerve', 'role': 'assistant'}]