What is a key function of a sump pump?

A sump pump is primarily designed to remove excess water from basements or crawl spaces. This function is critical in preventing flooding and water damage, which can lead to mold growth and structural issues in a home. When groundwater levels rise or when water seeps into a basement, the sump pump activates to pump out the accumulated water, directing it away from the foundation of the building.

In this context, the pump is placed in a sump basin, which is a pit dug in the basement or crawl space, and is triggered by water levels rising. This operational mechanism is essential for maintaining a dry and safe environment in areas prone to moisture buildup.

The other options do not accurately describe the primary function of a sump pump: it does not humidify the air, circulate warm air, or filter out pollutants. Instead, its sole purpose revolves around water management and flood prevention. Understanding this specialized role clarifies why the correct answer emphasizes the removal of excess water, ensuring the protection of residential properties from potential water hazards.