What naturally produced noble gas can diffuse into home basements and is associated with an increased risk of cancer?

Radon is a naturally occurring noble gas that is produced from the radioactive decay of uranium, which can be found in soil and rock. As radon is released from these materials, it can accumulate in lower areas such as basements, often leading to elevated concentration levels indoors. Being a radioactive gas, radon poses significant health risks, particularly since prolonged exposure to high levels can increase the likelihood of developing lung cancer. This is why radon is closely monitored in residential areas, especially those built on or near uranium-rich soil.

In contrast, the other noble gases listed, including helium, krypton, and xenon, do not demonstrate the same concerning health effects since they are stable, non-radioactive, and do not emanate from geological sources in significant amounts that would pose such risks. Therefore, radon stands out as the noble gas associated specifically with cancer risk, making it the correct answer to the question.