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
Most common cause of ophthalmia neonatorum is 
Select and explain. 
A. Chlamydia, B. Gonorrhoea, C. HSV, D. Staph aureus
A: Chlamydia
Answer: A: Chlamydia 
Explanation: Chlamydia is the most common cause and presents by 4-10 days. Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 419