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: Social & Preventive Medicine
[{'content': 'Age is an example of which of the following scales? \nSelect and explain. \nA. Nominal, B. Ordinal, C. Interval, D. Ratio', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Metric scale is fuher divided into interval and ratio scales. In a ratio scale, there is a definite zero point and it is correct to say that an age of 6 years is twice that of 3 years. Ref: Medical biostatistics, 1st edition pg: 99', 'role': 'assistant'}]