Which part of a drainage way is referred to as the upland sideslope?

The upland sideslope of a drainage way is best described as the sloping part of the drainage that directs water flow downhill. This area is positioned higher than the drainage way itself and typically consists of a gradient that facilitates the movement of water. This flowing water carries sediments and nutrients from the upland areas toward the lower elevations, contributing to the overall hydrology of the landscape. Although the other options refer to various topographical features related to drainage, they do not accurately capture the function and positioning of the upland sideslope in directing and channeling water flow. Therefore, recognizing the upland sideslope as the necessary pathway for water movement enhances the understanding of how drainage systems function within a given landscape.