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': 'The periodontal pocket principally contains \nSelect and explain. \nA. Living and degenerated leucocytes, B. Microorganisms, their products and debris, C. Gingival fluids and salivary mucin, D. Desquamated epithelial cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]