**Core Concept:** Morbid obesity is a severe form of obesity defined as a body mass index (BMI) greater than 40 kg/m². BMI is calculated by dividing an individual's weight in kilograms by the square of their height in meters.

**Why the Correct Answer is Right:** In the context of morbid obesity, the correct answer is **D** (40 kg/m²), as it represents the threshold for this condition. BMI is a simple and widely used method to evaluate body fat in adults based on their weight and height. When a person has a BMI of 40 kg/m² or higher, they are considered morbidly obese, which increases their risk for various health complications and conditions, such as type 2 diabetes, hypertension, dyslipidemia, and cardiovascular diseases.

**Why Each Wrong Option is Incorrect:**

A. **25 kg/m²**: This value is within the normal weight range (18.5 to 24.9 kg/m²), making it incorrect for identifying morbid obesity.

B. **30 kg/m²**: While this is within the overweight range (25 to 29.9 kg/m²), it is closer to the threshold for obesity (30 kg/m²) and does not accurately represent morbid obesity.

C. **35 kg/m²**: This value is within the obesity range (30 to 34.9 kg/m²) and does not accurately identify the morbid obesity condition.

**Clinical Pearl:** The World Health Organization (WHO) defines BMI categories using the following criteria:

1. Underweight: BMI <18.5 kg/m² 2. Normal weight: BMI 18.5 to 24.9 kg/m² 3. Overweight: BMI 25 to 29.9 kg/m² 4. Obesity: BMI 30 to 34.9 kg/m² 5. Morbid obesity: BMI ≥40 kg/m² **Correct Answer Explanation:** In morbid obesity, the body mass index (BMI) is significantly elevated, typically above 40 kg/m², indicating excessive body fat accumulation and increased risk for various health complications. The WHO categorizes BMI into different classes to assist in diagnosing obesity and its severity. In this question, the correct answer is **D** (BMI ≥40 kg/m²), which is the threshold for defining morbid obesity and the appropriate range to identify patients with this condition.