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: Pathology
[{'content': 'For a bacterium to be seriously considered in the etiology of dental caries, it must: \nSelect and explain. \nA. Exist regularly in the dental plaque, B. Produce extracellular amylopectins, C. Be lethal for gnotobiotic animals, D. Produce intracellular dextrans', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]