Which one of the following is a true statement about radon?

The true statement about radon is that it is a naturally occurring gas. Radon is produced from the natural breakdown of uranium in soil, rock, and water. It is found in varying levels throughout the environment and can infiltrate buildings, making it a significant concern for indoor air quality and health.

Radon's natural origin is pivotal in understanding its presence in homes and buildings, particularly in areas with high natural uranium content in the surrounding geology. While it is correct that radon is odorless, which would support the second choice, the most accurate identification comes from its classification as a naturally occurring element.

Radon can accumulate in different parts of a home, and while it often concentrates in basements due to proximity to the ground and possible entry points through cracks and openings, it is not exclusive to basements. Thus, saying it is found only in basements is an incomplete statement. Additionally, it is not synthetic; rather, it is a product of natural processes. Therefore, the correct assertions about radon rest firmly on its status as a naturally occurring gas.