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: Medicine
[{'content': 'Preobesity is defined as BMI of: March 2009 \nSelect and explain. \nA. 18.5-24.9, B. 25-29.9, C. 35-39.9, D. 40-44.9', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B: 25-29.9 BMI is an estimate of total body fat mass and is probably the most useful scale to define obesity. Obesity has been defined as a BMI >30.0 kg/m2 in World Health Organization (WHO) classification Body mass index (BMI), calculated from measured weight and height, was classified using the World Health Organization categories of underweight (BMI < 18.5 kg/m2), normal weight (BMI 18.5 to 24.9 kg/m2), pre-obesity (PreOB = BMI 25 to 29.9 kg/m2) and obesity (OB = BMI 30+ kg/m2)', 'role': 'assistant'}]