**Core Concept**
The recommended concentration of fluoride in school water fluoridation is essential for preventing dental caries in children. The optimal fluoride level helps in promoting tooth mineralization and preventing demineralization of tooth enamel.

**Why the Correct Answer is Right**
The recommended concentration of fluoride in school water fluoridation is typically around 0.7-1.2 milligrams per liter (mg/L). This range is supported by the Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) as it promotes optimal tooth mineralization and prevents dental caries. The fluoride concentration in school water is carefully monitored to ensure it falls within this range, as excessive fluoride intake can lead to dental fluorosis or even skeletal fluorosis in severe cases.

**Why Each Wrong Option is Incorrect**
**Option A:** A fluoride concentration of 0.2 mg/L is too low to effectively prevent dental caries, as it may not provide sufficient fluoride ions for optimal tooth mineralization.
**Option B:** A fluoride concentration of 5 mg/L is excessively high and can lead to dental fluorosis, a condition characterized by white or brown spots on teeth due to excessive fluoride exposure.
**Option C:** A fluoride concentration of 1.5 mg/L is higher than the recommended range and may increase the risk of skeletal fluorosis in children, a condition caused by excessive fluoride intake leading to bone damage.

**Clinical Pearl / High-Yield Fact**
The optimal fluoride concentration in school water fluoridation is a critical factor in preventing dental caries in children. It is essential to monitor and maintain a fluoride concentration within the recommended range to avoid adverse effects.

**Correct Answer: C. 1.2 milligrams per liter (mg/L)**