**Core Concept**
Vitamin A is an essential nutrient for vision, immune function, and reproduction. The American Academy of Pediatrics recommends Vitamin A supplementation in infants starting at a certain age to prevent vitamin A deficiency.

**Why the Correct Answer is Right**
The correct age for starting Vitamin A supplementation is 6 months. This is because breast milk alone may not provide sufficient Vitamin A for infants beyond 6 months. Additionally, Vitamin A plays a crucial role in the development of the infant's visual system, and supplementation at this age helps support normal vision development. The mechanism of Vitamin A action involves the retinol-binding protein (RBP) and the transport of retinol to the liver, where it is stored and released as needed.

**Why Each Wrong Option is Incorrect**
**Option A:** Starting Vitamin A supplementation at birth is not recommended, as breast milk provides sufficient Vitamin A for the first 6 months of life.
**Option B:** While Vitamin A is essential for vision, starting supplementation at 1 year of age is too late, as the visual system is already developed.
**Option C:** Vitamin A supplementation is not typically recommended for infants beyond 12 months of age, unless there is a specific indication for supplementation.

**Clinical Pearl / High-Yield Fact**
Remember the "A" in "A" day: "A" (Vitamin A) supplementation is recommended at 6 months of age to support normal vision development.

**Correct Answer:** C.