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: Unknown
[{'content': 'Most common cause of ophthalmia neonatorum : \nSelect and explain. \nA. Chlamydia, B. Gonorrhoea, C. HSV, D. Staph aureus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Chlamydia is the most common cause and presents by 4-10 days.', 'role': 'assistant'}]