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': "In Dean's fluorosis index (WHO Assessment Form), code 2 indicates \nSelect and explain. \nA. Very mild fluorosis, B. Mild fluorosis, C. Moderate fluorosis, D. Severe fluorosis", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]