This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Streptococci, Subject name: Microbiology
[{'content': 'Which one of the following organisms is the most frequent cause of acute pyogenic meningitis in adults: \nSelect and explain. \nA. Streptococcus pneumoniae, B. Neisseria meningitis, C. Haemophilus influenza, D. Listeria monocytogenes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Streptococcus pneumoniaeRef: Dhingra 5th ed. /61y 81', 'role': 'assistant'}]