**Core Concept**
Broca's index is a measure of ideal body weight for adults, used to assess obesity. It is calculated as 2.7 times the height in meters minus 100. This index helps in determining the ideal weight range for an individual based on their height.

**Why the Correct Answer is Right**
Broca's index is a specific measure of ideal body weight, which is essential in assessing obesity. The calculation of 2.7 times the height in meters minus 100 provides a more accurate estimate of ideal body weight compared to other indices. This index is particularly useful in clinical settings to assess weight status and to plan appropriate management strategies for obese patients.

**Why Each Wrong Option is Incorrect**
**Option A:** Ponderal index is another measure of leanness of a person calculated by dividing a person's height in meters by the cube of their weight in kilograms. It does not specifically measure ideal body weight.
**Option B:** Quetelet index, also known as the body mass index (BMI), is a widely used measure of obesity but it does not take into account muscle mass and bone density. It is calculated as weight in kilograms divided by the square of height in meters.
**Option D:** Corpulence index is another measure of obesity, but it is not as commonly used as Broca's index. It is calculated as the ratio of actual weight to ideal weight.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that Broca's index is a more accurate measure of ideal body weight compared to BMI, especially in individuals with a high muscle mass or bone density.

**Correct Answer:**
✓ Correct Answer: A. Broca's index