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
During cap stage signalling in the odontogenic epithelium is done by: 
Select and explain. 
A. Enamel knot., B. Enamel cord., C. Enamel septum., D. Enamel navel.
A: Enamel knot.
Answer: A: Enamel knot. 
Explanation: Recent studies have shown that enamel knot acts as a signaling center as many important growth factors are expressed by the cells of the enamel knot and thus they play an important part in determining the shape of the tooth.