Which of the following is a type of water outflow?

The choice of stream drainage as a type of water outflow is based on its fundamental role in the hydrologic cycle. Stream drainage refers to the process by which water from various sources, such as rainfall, snowmelt, or groundwater, is channeled into streams and rivers. This movement is crucial for transporting water away from an area, which helps in maintaining the water balance in ecosystems and is essential for the health of aquatic environments. It also plays a significant role in hydrology, influencing flood dynamics, nutrient cycling, and habitat connectivity.

The other options do not represent a type of water outflow in the same way. Evaporation, while a part of the water cycle, involves the transition of water from liquid to vapor and does not necessarily imply an outflow mechanism in a drainage context. Legal compartmentalization pertains to regulatory frameworks and land management practices rather than physical movement of water. Pollutant diversion focuses on managing contaminants in water systems and does not inherently describe the outflow of water itself. Thus, stream drainage distinctly exemplifies a natural form of water outflow, which is why it is the correct answer.