What is runoff?

Runoff refers to the flow of water from land, specifically resulting from precipitation such as rain or melting snow. This natural process is crucial in the water cycle as it directs excess water from surfaces like roads, fields, and other landscapes into nearby rivers, lakes, and ultimately the ocean. Runoff is a key component in the transport of nutrients and sediments, influencing freshwater and marine ecosystems.

In contrast, other options do not accurately define runoff. The evaporation of water from the ocean pertains to the transition of water from liquid to vapor state, which is distinctly different from runoff. The process of water retreating from the shore is related to tidal movements or waves, rather than the flow of water across land. Lastly, the collection of seawater in a lagoon describes a geographical feature rather than a process involving water movement from land. Therefore, the definition aligning with runoff encompasses its role in land-water interaction following precipitation, making it the correct choice.