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
A 56 year old man has painful weeping rashes over the upper eyelid and forehead for the last 2 days along with ipsilateral acute punctate keratopathy. About a year back, he had chemotherapy for Non-Hodgkin's lymphoma. There is no other abnormality. Which of the following is the most likely diagnosis? 
Select and explain. 
A. Impetigo, B. Systemic Lupus Erythematosus, C. Herpes Zoster, D. Pyoderma gangrenosum
C: Herpes Zoster
Answer: C: Herpes Zoster 
Explanation: C i.e. Herpes zoster