This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
[{'content': 'Variables in the form of mild,moderate,severe is given.Method used to analyse is \nSelect and explain. \nA. Nominal, B. Ordinal, C. Interval, D. Variance', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ref:Park's Textbook of Preventive and Social Medicine 25th Ed", 'role': 'assistant'}]