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': 'Hemifacial microsomia occurs during: \nSelect and explain. \nA. Formation of germ layer, B. Migration of neural crest cells, C. At the time of organ formation, D. Final differentiation of tissue', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]