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': 'Biological width means \nSelect and explain. \nA. Sum of connective tissue and junctional epithelium, B. Distance from the tip of the papilla to the base of the sulcus, C. Distance from marginal gingiva to muco-gingival junction, D. Distance from incisal edge of the tooth to muco-gingival junction', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]