**Core Concept**
Preterm very low birth weight (VLBW) infants have limited calcium and vitamin D stores, making supplementation crucial to prevent rickets, osteopenia, and other bone-related complications. Fortified breast milk is essential to meet their specific nutritional needs.

**Why the Correct Answer is Right**
VLBW infants require higher doses of calcium and vitamin D to support bone growth and mineralization. The American Academy of Pediatrics recommends the following supplementation: Calcium: 200-300 mg/kg/day, divided into 2-3 doses; Vitamin D: 400 IU/kg/day. These doses are essential to prevent hypocalcemia, tetany, and other bone-related issues.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely too low in calcium (100 mg/kg/day) and vitamin D (200 IU/kg/day), which may not meet the nutritional needs of preterm VLBW infants.
**Option B:** This option is incorrect as it suggests a single daily dose of calcium (400 mg/kg/day) and vitamin D (600 IU/kg/day), which may not be adequate for VLBW infants.
**Option C:** This option is likely too high in calcium (500 mg/kg/day) and vitamin D (800 IU/kg/day), which may lead to hypercalcemia and other complications.

**Clinical Pearl / High-Yield Fact**
Preterm VLBW infants require individualized calcium and vitamin D supplementation based on their birth weight, gestational age, and laboratory values. Regular monitoring of serum calcium and vitamin D levels is essential to adjust supplementation accordingly.

**Correct Answer: C. 500 mg/kg/day calcium and 800 IU/kg/day vitamin D.**