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': "The commor'est cause of hypopyon is: \nSelect and explain. \nA. Moraxella, B. Gonococcus, C. Pneumococcus, D. Staphylococcus", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Pneumococcus', 'role': 'assistant'}]