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': 'In cap stage, regulating factor for cusp shape formation is present in \nSelect and explain. \nA. Dental papilla, B. Dental follicle, C. Inner enamel epithelium, D. Enamel knot', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Enamel Knot: The cells in the center of the enamel organ are densely packed to form enamel knot.\nEnamel cord: It is the vertical extension of the enamel knot.\nEnamel Septum: The enamel cord extends to meet the outer enamel epithelium and form enamel septum.\nEnamel Navel: It is the small depression at the point of meeting of enamel cord and outer enamel epithelium.\nEnamel niche is the apparent structure created by the plane of histological sections\xa0cutting through a curved dental lamina so that mesenchyme is surrounded by the dental epithelium. It appears as a double attachment of dental lamina to the overlying epithelium.\n\nRecent studies shows that enamel knot acts as a signaling center expressing growth factors which play an important role in determining the shape of the tooth', 'role': 'assistant'}]