## Core Concept
Fluorosis is a condition caused by excessive intake of fluoride, leading to skeletal and dental manifestations. It can occur in two forms: dental fluorosis, which affects the teeth, and skeletal fluorosis, which affects the bones. The primary source of excessive fluoride is usually contaminated water.

## Why the Correct Answer is Right
The correct answer, ., implies that the statement regarding fluorosis that is not true needs to be identified among the options. Typically, fluorosis is associated with areas where the water supply has high levels of fluoride. Dental fluorosis leads to discoloration and pitting of teeth, while skeletal fluorosis can cause bone pain, osteosclerosis, and calcification of tendons and ligaments.

## Why Each Wrong Option is Incorrect
- **Option A:** Without specific details on what option A states, we can infer that if it accurately describes a consequence or characteristic of fluorosis, it would be a true statement regarding the condition.
- **Option B:** Similarly, if option B is a true statement about fluorosis, it would align with known facts about the condition, such as its prevalence in areas with high fluoride water levels.
- **Option C:** This option would also be incorrect if it presents a verified fact about fluorosis, such as the fact that it can lead to dental and skeletal issues.
- **Option D:** Given that . is the correct answer, option D must contain a statement that does not accurately describe fluorosis or is an exception to the characteristics of the condition.

## Clinical Pearl / High-Yield Fact
A key point to remember is that fluorosis is often seen in regions with high levels of fluoride in the drinking water, typically above 1.5 mg/L. Prevention involves adjusting the fluoride levels in community water supplies to optimal levels for dental health (around 0.7-1.2 mg/L) and promoting awareness about the risks of excessive fluoride intake.

## Correct Answer: D.