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': 'What are the characteristics of the primary (initial) bacterial colonizers of the tooth in dental plaque formation? \nSelect and explain. \nA. Gram-negative facultative, B. Gram-positive facultative, C. Gram-negative anaerobic, D. Gram-positive anaerobic', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Streptococcal and Actinomyces species are initial colonizers of dental plaque. They are grampositive, facultative micro-organisms.', 'role': 'assistant'}]