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': 'Number of enamel rods has been estimated in lower incisors as \nSelect and explain. \nA. 5 million, B. 10 million, C. 2 million, D. 12 million', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]