**Core Concept**
The 'at risk' infant is a term used to describe newborns who may be vulnerable to various health risks or complications due to factors such as prematurity, low birth weight, or congenital anomalies. The criteria for identifying 'at risk' infants are crucial for early intervention and prevention of potential health problems.

**Why the Correct Answer is Right**
To identify 'at risk' infants, healthcare providers assess various factors, including birth weight, gestational age, and the presence of congenital anomalies. Infants born preterm (less than 37 weeks of gestation) or with low birth weight (less than 2,500 grams) are at increased risk for respiratory distress syndrome, hypoglycemia, and other complications. Additionally, infants with congenital anomalies, such as heart defects or chromosomal abnormalities, require close monitoring and specialized care.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a recognized criterion for identifying 'at risk' infants. Birth weight and gestational age are well-established risk factors, but this option does not provide a clear or relevant criterion.
**Option B:** This option is incorrect because it is a recognized criterion for identifying 'at risk' infants. Prematurity and low birth weight are well-established risk factors for various health complications.
**Option C:** This option is incorrect because it is a recognized criterion for identifying 'at risk' infants. Congenital anomalies, such as heart defects or chromosomal abnormalities, require close monitoring and specialized care.

**Clinical Pearl / High-Yield Fact**
When assessing 'at risk' infants, healthcare providers should focus on the following key factors: birth weight, gestational age, and the presence of congenital anomalies. Early identification of these risk factors enables timely intervention and prevention of potential health problems.

**Correct Answer:** None of the above