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': 'Incremental lines of striae of Retzius denote: \nSelect and explain. \nA. Active period., B. Rest Period., C. Mixed activity., D. Hyperactive but normal period.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]