**Core Concept**
Acute malnutrition is a condition characterized by a rapid onset of malnutrition, often due to inadequate dietary intake, increased energy expenditure, or both. This condition can lead to severe health consequences, including weight loss, muscle wasting, and impaired immune function. The underlying pathophysiology involves a negative energy balance, leading to a depletion of body reserves, particularly in vulnerable populations such as children and pregnant women.

**Why the Correct Answer is Right**
The correct manifestation of acute malnutrition is weight-for-height < -2 Z-scores, also known as wasting. This is because acute malnutrition primarily affects the muscle mass and body fat, leading to a disproportionate reduction in weight in relation to height. The Z-score is a statistical measure that compares an individual's weight-for-height to a reference population, allowing for the identification of acute malnutrition. In contrast, stunting, which is a manifestation of chronic malnutrition, is characterized by a low height-for-age. **Why Each Wrong Option is Incorrect** **Option A:** This option is incorrect because it does not specifically refer to a manifestation of acute malnutrition. While weight loss is a common feature of malnutrition, it is not a specific or sensitive indicator of acute malnutrition. **Option B:** This option is incorrect because it is more characteristic of chronic malnutrition, which is a result of prolonged inadequate nutrition, often during critical periods of growth and development. **Option C:** This option is incorrect because it is not a specific or sensitive indicator of acute malnutrition. While edema can occur in severe malnutrition, it is not a primary manifestation of acute malnutrition. **Clinical Pearl / High-Yield Fact** The World Health Organization (WHO) uses the following criteria to diagnose acute malnutrition: weight-for-height < -2 Z-scores (wasting), mid-upper arm circumference (MUAC) < 115 mm (indicative of severe acute malnutrition), and edema. These criteria are essential for early detection and treatment of acute malnutrition. **Correct Answer:** C. Weight-for-height < -2 Z-scores