**Core Concept**
Calcium is an essential mineral for infants, playing a vital role in the development of bones, teeth, and muscles. Adequate calcium intake during infancy is crucial for establishing optimal bone density and preventing conditions such as rickets.

**Why the Correct Answer is Right**
The daily calcium requirement of infants varies based on age. For infants from 0 to 6 months, the recommended daily intake is approximately 200-260 mg. This requirement increases to 260-300 mg for infants from 7 to 12 months. The exact requirement may differ based on factors such as the infant's growth rate and overall health status. The Institute of Medicine recommends these values, which are essential for maintaining healthy bone development.

**Why Each Wrong Option is Incorrect**
**Option A:** This option does not provide a specific daily calcium requirement for infants, making it an incorrect choice.
**Option B:** This option is not a valid daily calcium requirement for infants, as it does not align with established recommendations.
**Option C:** This option does not accurately reflect the daily calcium requirement for infants, which is lower than the adult requirement.

**Clinical Pearl / High-Yield Fact**
Infants require adequate calcium intake to support optimal bone growth and development. A deficiency in calcium can lead to conditions such as rickets, which can cause skeletal deformities and other complications.

**Correct Answer: D. 260-300 mg**