## Core Concept
Chronic malnutrition, also known as stunting, is a condition where individuals, particularly children, experience growth retardation due to prolonged inadequate nutrition. It is often measured through anthropometric indicators that reflect long-term nutritional status. The key to assessing chronic malnutrition lies in evaluating growth over time.

## Why the Correct Answer is Right
The correct answer, , is measured by **Height-for-Age (HFA) Z-scores**. This indicator compares a child's height to a reference population's height at the same age, expressed as a Z-score. A Z-score below -2 indicates that the child's height is more than 2 standard deviations below the median height of the reference population, signifying stunting and chronic malnutrition. This measure reflects long-term nutritional status and is crucial for assessing the impact of chronic malnutrition on growth and development.

## Why Each Wrong Option is Incorrect
* **Option A:** - This option refers to **Weight-for-Height (WFH) Z-scores**, which is an indicator of acute malnutrition. It does not accurately reflect chronic malnutrition.
* **Option B:** - This option represents **Weight-for-Age (WFA) Z-scores**, which can indicate both acute and chronic malnutrition but does not specifically measure chronic malnutrition.
* **Option D:** - This option, **Body Mass Index (BMI)**, is used in adults and adolescents to assess nutritional status but does not specifically measure chronic malnutrition in children.

## Clinical Pearl / High-Yield Fact
A crucial point to remember is that **chronic malnutrition (stunting) is best assessed by Height-for-Age Z-scores**. This indicator helps in identifying populations at risk and in evaluating the effectiveness of long-term nutritional interventions. Understanding the difference between acute (wasting) and chronic (stunting) malnutrition is vital for appropriate public health and clinical interventions.

## Correct Answer: C. Height-for-Age.