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 distance from the CEJ to the base of the pocket is a measure of \nSelect and explain. \nA. Clinical attachment level, B. Gingival recession, C. Probing pocket depth, D. Alveolar bone loss', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The periodontal examination includes probing pocket depth (distance from the gingival margin to the base of the pocket) and clinical attachment level (distance from the CEJ to the base of the pocket). Both of these measures are made using a periodontal probe. Gingival recession can be measured as the distance from the CEJ to the free gingival margin. Alveolar bone loss is measured radiographically', 'role': 'assistant'}]