**Core Concept**
The question is asking about a height-independent index, which refers to a measure used to assess body composition or nutritional status that does not depend on an individual's height. This is particularly useful in clinical settings where height may not be available or may vary greatly among patients.

**Why the Correct Answer is Right**
The correct answer is the Body Mass Index (BMI) is not height independent. However, the correct answer to the question is the one that is height independent. One such index is the **Quetelet Index**, also known as the **Relative Weight** or **Body Mass Index Relative to Height**. However, the correct answer is the **Relative Body Weight (RBW)**, which is calculated as the body weight in kilograms divided by the ideal body weight in kilograms for the same height.

**Why Each Wrong Option is Incorrect**
* **Option A:** Not relevant to the question.
* **Option B:** Not a height-independent index.
* **Option C:** Not a height-independent index.

**Clinical Pearl / High-Yield Fact**
The Quetelet Index is also known as the **Relative Weight**, and it is calculated as the body weight in kilograms divided by the ideal body weight in kilograms for the same height. This index is useful in assessing body composition and nutritional status in patients.

**Correct Answer: C. Relative Body Weight (RBW)**