**Core Concept**
Gomez classification is a method used to categorize protein-energy malnutrition (PEM) in children based on their weight-for-age and height-for-age. It is a widely used tool in pediatric medicine to assess the severity of malnutrition and guide treatment.

**Why the Correct Answer is Right**
The Gomez classification categorizes malnutrition into four stages: Grade 0 (normal), Grade 1 (mild), Grade 2 (moderate), and Grade 3 (severe). The classification is based on the child's weight-for-age and height-for-age, with Grade 3 being the most severe form of malnutrition. Children with Grade 3 malnutrition have a significant reduction in weight and height, indicating a high risk of mortality.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Gomez classification does not categorize malnutrition based on age alone. While age is a factor in assessing growth and development, the Gomez classification takes into account both weight-for-age and height-for-age.

**Option B:** This option is incorrect because Gomez classification does not use a numerical scale to assess malnutrition. The classification is based on four stages (Grade 0 to Grade 3), not a numerical value.

**Option C:** This option is incorrect because Gomez classification does not use a grading system based on the child's symptoms alone. While symptoms such as weight loss and edema may be present, the classification is based on a more objective assessment of weight-for-age and height-for-age.

**Clinical Pearl / High-Yield Fact**
The Gomez classification is a simple and effective tool for assessing protein-energy malnutrition in children. However, it is essential to note that the classification should be used in conjunction with other clinical assessments and diagnostic tests to determine the underlying cause of malnutrition.

**Correct Answer: C. Gomez classification categorizes malnutrition into four stages: Grade 0 (normal), Grade 1 (mild), Grade 2 (moderate), and Grade 3 (severe).**