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': 'Which of the following is the important factor to be considered before attempting to close a midline diastema using a removable appliance? \nSelect and explain. \nA. The size of the teeth, B. Age of the patient, C. Vitality of the teeth, D. Amount of overjet', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]