Fluoride content in water is removed by:
**Core Concept**
Water fluoridation is a public health measure to prevent dental caries. However, excessive fluoride intake can lead to dental fluorosis and skeletal fluorosis. Therefore, it is essential to remove excess fluoride from drinking water.
**Why the Correct Answer is Right**
Activated alumina is a type of adsorbent that is widely used to remove fluoride from water. It works by forming a complex with fluoride ions, which prevents them from passing through the water treatment process. This is particularly useful in areas where the natural fluoride content in water is high, as it helps to prevent the adverse effects of excessive fluoride intake.
**Why Each Wrong Option is Incorrect**
* **Option A:** Ion exchange resins are used to remove other ions such as sodium, potassium, and heavy metals from water, but they are not effective in removing fluoride.
* **Option B:** Reverse osmosis is a membrane-based technology that removes a wide range of contaminants from water, but it is not the most cost-effective method for removing fluoride.
* **Option C:** Ultraviolet (UV) light is used to disinfect water by killing bacteria and viruses, but it has no effect on fluoride levels.
**Clinical Pearl / High-Yield Fact**
Activated alumina is a highly effective and cost-efficient method for removing fluoride from water, making it a popular choice for water treatment plants around the world.
**Correct Answer:** C. Activated alumina.