## Core Concept
The question pertains to an obesity index that is independent of height. In the assessment of obesity, various indices are used, including body mass index (BMI), waist circumference, waist-to-hip ratio, and others. However, BMI is a height-dependent measure. Therefore, we are looking for an index that does not rely on height to categorize or quantify obesity.

## Why the Correct Answer is Right
The correct answer, **Waist Circumference**, is a measure that does not depend on height. It is a direct anthropometric measurement that reflects central obesity. Waist circumference is used as an indicator of visceral fat and metabolic health. It is measured at the midpoint between the lower rib margin and the iliac crest. This measure is particularly useful because it does not require height measurements, making it a height-independent index of obesity.

## Why Each Wrong Option is Incorrect
- **Option A:** BMI (Body Mass Index) is a height-dependent measure calculated as weight in kilograms divided by the square of height in meters (kg/m^2). Therefore, it does not fit the criteria of being height-independent.
- **Option B:** Waist-to-Hip Ratio (WHR) does involve measurements that could be considered height-independent (waist and hip circumference), but it is not listed as the correct answer here, and another option directly answers the question more straightforwardly.
- **Option D:** Skinfold measurements are another method to assess body fat but are not typically considered an "index" in the same way waist circumference or BMI.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that **waist circumference is a critical measure for assessing central obesity and metabolic risk**. For men, a waist circumference of ≥40 inches (102 cm) and for women ≥35 inches (88 cm) is considered indicative of increased risk. This measure is particularly useful in clinical settings where assessing height may not be feasible or when evaluating the risk of metabolic syndrome.

**Correct Answer: C. Waist Circumference.**