Which choice best describes a retention basin?

A retention basin is specifically designed to store stormwater runoff and typically maintains a permanent pool of water. This is a key characteristic that differentiates it from other types of basins. The presence of a permanent pool allows for better management of stormwater by facilitating the natural processes of sedimentation and biological filtration, which can improve water quality before it is released into downstream systems.

In contrast, a retention basin is not intended for temporary storage; while it can handle variations in water levels due to storm events, its main purpose is to retain water. Additionally, a retention basin is not limited to collecting debris nor is it merely a channel for directing water away. Instead, it serves the vital role of storing water to manage peak flows and mitigate flooding, which can be critical in urban planning and environmental management. Thus, the defining feature of a retention basin as a system that contains a permanent pool of water is what makes that choice the most accurate description.