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: Dental
[{'content': 'In deep older plaque \nSelect and explain. \nA. Streptococci and actinomyces are replaced by rod like organism, B. Streptococci are completely replaced by neisseria, C. Streptococci actinomyces and veilonella remain prominent, D. Actinomyces are completely replaced by streptococci', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]