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': 'When the black band of a CPITN probe is completely visible while in gingival sulcus, it means \nSelect and explain. \nA. The individual has advanced periodontal disease, B. The individual has pockets between 4 and 5 mm, C. The individual needs comprehensive periodontal surgery, D. The individual has calculus and needs scaling and oral hygiene instructions', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]