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': 'Under light microscopy, an active synthetic cell demonstrates \nSelect and explain. \nA. Flattened nucleus, B. Open faced nucleus, C. Close faced nucleus, D. Vesicular nucleus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]