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 most frequent bacterial agent causing nongranulomatous uveitis is: \nSelect and explain. \nA. Staphylococcus, B. Streptococcus, C. Pneumococcus, D. Influenza bacillus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Streptococcus', 'role': 'assistant'}]