## **Core Concept**
Quetelet's index, commonly known as the Body Mass Index (BMI), is a statistical measurement used to assess an individual's weight status in relation to their height. It is a key indicator in epidemiology and public health for evaluating obesity and underweight conditions.

## **Why the Correct Answer is Right**
The correct formula for Quetelet's index or BMI is weight in kilograms divided by the square of height in meters, which is expressed as **kg/m²**. This measurement provides a simple, widely accepted method to categorize individuals into various weight categories such as underweight, normal weight, overweight, and obese. The World Health Organization (WHO) defines the following BMI categories: underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), and obese (≥30 kg/m²). ## **Why Each Wrong Option is Incorrect** - **Option A:** This option does not represent the correct formula for BMI or Quetelet's index. - **Option B:** Similarly, this option does not accurately depict the BMI formula. - **Option D:** This option also does not correctly represent the Quetelet's index or BMI. ## **Clinical Pearl / High-Yield Fact** A crucial point to remember is that while BMI is a useful tool for population-level assessments and clinical screenings, it has limitations. For instance, it does not differentiate between lean body mass and body fat, which can lead to misclassification of athletes or individuals with a high muscle mass as overweight or obese. Despite these limitations, BMI remains a widely used and accepted measure due to its simplicity and utility in assessing weight status at a population level. ## **Correct Answer:** B. $Weight (kg)/ Height (m)^2$.