What does the term "river basin" refer to?

The term "river basin" specifically refers to the area drained by a river and its tributaries. This includes all the land that collects rainfall and snowmelt, which then flows into the river system. A river basin is essentially the entire geography that contributes water to a river, making it critical for understanding hydrology, water resource management, and ecological studies.

In contrast, other options do not accurately represent the definition of a river basin. For instance, the definition tied to lakes impacted by dams refers more to specific water bodies rather than a drainage area. The geological makeup of river rocks involves more detailed analysis of the materials found in riverbeds and does not pertain to the broader area involved in drainage. Finally, a particular type of wetland highlights a specific aquatic ecosystem that may exist within a basin but does not encapsulate the full meaning of a river basin itself. Hence, the correct understanding is about the comprehensive area influencing a river's flow.