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': 'Cap stage contains the following transitory structure: \nSelect and explain. \nA. Enamel matrix., B. Stratum intermedium., C. Cervical loop., D. Enamel knot,Enamel cord,Enamel niche.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]