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': 'The incisive papilla in the edentulous maxillary arch acts as a guideline to proper placement of the maxillary central incisors. The central incisors are generally found to be ________ mm anterior to a Line bisecting the incisive papilla: \nSelect and explain. \nA. 8 to 10mm, B. 6 to 8mm, C. 4 to 6mm, D. 5 to 7mm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]