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': 'Dental lamina is active up to: \nSelect and explain. \nA. 1 year, B. 2 years, C. 4 years, D. 5 years', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Even after 5 years, it may be active in 3rd molar area\xa0after it has disappeared elsewhere. Remnants of dental lamina persist as epithelial pearls or islands within the jaws and gingiva.', 'role': 'assistant'}]