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': 'Epithelial mesenchymal interaction in tooth development is an example of: \nSelect and explain. \nA. Cell signaling, B. Calcification, C. Histodifferentiation, D. Morphodifferentiation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Cells interact through a system of effectors, modulators, and receptors called cell signaling. An example of such a system is epithelial-mesenchymal interaction in tooth development. The precursor cells, odontoblast and ameloblast, establish a positional relationship by means of effectors and receptors that are on the cell surface.', 'role': 'assistant'}]