How does the geology of an area influence radon levels?

The correct answer highlights that different rock types can emit varying amounts of radon due to their geological composition. Radon is a natural radioactive gas produced from the decay of uranium present in many types of rocks, particularly granites and other igneous rocks that contain higher uranium levels. Areas with these rock types can exhibit higher radon concentrations, while sedimentary rocks may emit less radon. Understanding the geological makeup of an area is crucial for assessing radon risk, as it directly correlates with the potential for radon generation and accumulation in buildings and soil.

In contrast, the other options do not accurately represent the relationship between geology and radon levels. Soil composition, for instance, does play a role in radon emissions, as it can either allow radon to escape into the atmosphere or trap it closer to the ground. Additionally, while man-made structures can influence radon dynamics through ventilation and building materials, the primary emission source is geological rather than anthropogenic. Lastly, geology is indeed a significant factor affecting radon levels, contradicting the assertion that it has no impact.