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: Microbiology
Herpes zoster ophthalmicus is 
Select and explain. 
A. Reactivation of herpes in optic nerve, B. Reactivation of herpes in trigeminal nerve, C. Reactivation of herpes in occulomotor nerve, D. herpes in immunocompromised
B: Reactivation of herpes in trigeminal nerve
Answer: B: Reactivation of herpes in trigeminal nerve 
Explanation: It is due to reactivation of herpes in ophthalmic branch of trigeminal nerve.