Which of the following best describes Radon?

Radon is a radioactive gas that naturally occurs from the decay of uranium in soil, rock, and water. It is colorless and odorless, which makes it difficult to detect without specific testing equipment. The key concern with radon is its potential health risks, particularly its association with lung cancer. When radon is inhaled, its radioactive particles can damage lung tissue, leading to an increased risk of developing lung cancer over time.

The other descriptions do not accurately represent radon. A statement suggesting it poses no health risks misrepresents the significant health implications associated with radon exposure. Similarly, describing it as a chemical used for water treatment is incorrect, as radon's presence is considered a contamination concern rather than a treatment agent. Lastly, labeling it as a noticeable, pungent gas found in municipal water is misleading because radon is neither noticeable nor has a recognizable odor, making this description inaccurate. Thus, the most accurate and informative answer is that radon is a radioactive gas that increases lung cancer risk.