This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
[{'content': 'Most common cause of ophthalmia neonatorum is \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. Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 419', 'role': 'assistant'}]