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
Reservoir of dividing cells for the growing enamel organ 
Select and explain. 
A. Temporary structures, B. Enamel knot, C. Enamel cord, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Both enamel knot and enamel cord of stellate reticulum are temporary structures and act as a reservoir dividing cells S the growing enamel organ.