## Core Concept
The protein requirement for infants varies by age and is crucial for growth and development. Infants rely heavily on breast milk or formula for their nutritional needs, including protein. The recommended protein intake for infants is typically expressed in grams per kilogram of body weight per day.

## Why the Correct Answer is Right
The correct answer, **1.6-2.2 g/kg/day**, reflects the recommended protein intake for infants aged 0-6 months. This range supports optimal growth, development, and maintains a balance with other nutrients. Breast milk, which provides about 0.8-1.2 g/kg/day of protein, is often used as a reference for infant nutrition guidelines.

## Why Each Wrong Option is Incorrect
- **Option A:** This option suggests a lower protein requirement. While breast milk provides around 0.8-1.2 g/kg/day of protein, the total requirement including from other sources for 0-6 months infants is generally considered to be higher.
- **Option B:** This option provides a range but does not align with established nutritional guidelines for infants of this age group.
- **Option D:** This option suggests a significantly higher protein requirement than recommended, which could potentially overburden the infant's kidneys and does not align with standard nutritional guidelines.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the protein needs of infants are met largely through breast milk or infant formula, which are designed to mimic the composition of breast milk. For infants aged 0-6 months, exclusive breastfeeding is recommended, which inherently provides the necessary protein and other nutrients within the range of **1.6-2.2 g/kg/day**.

## Correct Answer: C. 1.6-2.2 g/kg/day