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
[{'content': 'Commonest causative organism of corneal ulcer is: \nSelect and explain. \nA. Pneumococci, B. Streptococci, C. Staphylococci, D. Fungal', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Staphylococci', 'role': 'assistant'}]