Watersheds or drainage basins can drain into which of the following?

Watersheds, also known as drainage basins, are areas of land where all the water under it or draining off of it goes into the same place, typically a river, lake, or ocean. When considering the options, the most relevant choice is rivers because they act as channels that collect and transport water that flows from the surrounding landscape within the watershed.

The other options, while they may have some relation to water, do not directly serve as endpoints for water drainage. Forests and deserts can exist within or adjacent to watersheds but do not collect and transport water in the way that rivers do. Mountains, similarly, may be part of the watershed area, but they do not function as a drainage point. Ultimately, rivers are the primary feature where watersheds culminate their flow, making it the correct answer in this context.