How is Body Mass Index (BMI) calculated?

Body Mass Index (BMI) is calculated by taking a person's weight in kilograms and dividing it by their height in meters squared. This calculation provides a numerical value that is used to assess whether a person has a healthy body weight for a given height.

The formula, BMI = weight (kg) / height (m^2), ensures that the weight is appropriately scaled to the individual's height, accounting for how body weight relates to height in a squared manner. This is important because it gives a more accurate representation of body fat and potential health risks associated with being underweight, overweight, or obese.

The other options are not valid calculations for BMI. For instance, option A, which suggests height divided by weight, does not accurately represent the relationship needed. Option B, simply subtracting height from weight, lacks a scientific foundation relating to body composition. Lastly, option D, which depicts height squared divided by weight, is also incorrect, as it inverts the necessary relationship between weight and height necessary to calculate BMI accurately. Thus, the correct answer encapsulates the proper relationship between weight and height that BMI is designed to measure.