## Core Concept
Severe acute malnutrition (SAM) is a condition characterized by a significant deviation from normal growth patterns, often due to inadequate nutrition. The diagnosis of SAM is primarily based on anthropometric measurements. The World Health Organization (WHO) provides specific criteria for the diagnosis of SAM.

## Why the Correct Answer is Right
The WHO criteria for SAM include a very low weight-for-height (below -3 z-scores of the WHO child growth standards), visible severe wasting, or the presence of nutritional oedema. These criteria help in identifying children who are at a high risk of mortality and require immediate nutritional intervention.

## Why Each Wrong Option is Incorrect
* **Option A:** Not specified, but generally, criteria such as MUAC (Mid-Upper Arm Circumference) less than 115 mm in children aged 6–59 months, and visible severe wasting are included.
* **Option B:** Similarly, not detailed, but usually involves a weight-for-height below -3 z-scores.
* **Option D:** Also not detailed, but often includes nutritional oedema.

## Why Option C is Correct and Others are Incorrect (Specifics Needed for Complete Response)
Given that specific details for each option (A, B, C, D) are not provided, we infer based on common knowledge about SAM diagnosis. Typically, SAM diagnosis involves:
- Weight-for-height below -3 z-scores.
- MUAC less than 115 mm.
- Visible severe wasting.
- Nutritional oedema.

## Clinical Pearl / High-Yield Fact
A key point to remember is that SAM is diagnosed primarily through anthropometric measurements, and the cut-off for severe acute malnutrition is a weight-for-height z-score of less than -3, or a MUAC of less than 115 mm in children aged 6 to 59 months.

## Correct Answer: C.