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': 'What is the characteristic of normal distribution? \nSelect and explain. \nA. Mean = Median = mode, B. Mean is 1, SD-zero, C. Curve skewed towards the left, D. Curve skewed towards the right', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]