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': 'Grading disease severity as mild, moderate, severe is an example of which scale? \nSelect and explain. \nA. Nominal, B. Ordinal, C. Interval, D. Ratio', 'role': 'user'}, {'content': 'Answer: B \nExplanation: There are characteristics that should be measured in terms of quantities but nonavailability of a good instrument compels measure in terms of what is called an ordinal scale. Example is disease severity measured as mild, moderate or severe. Ref: Medical biostatistics, 1st edition pg: 99', 'role': 'assistant'}]