Concept:A river’s upper course is steep and erosive, creating features such as waterfalls and rapids.Explanation:In the upper course, the river flows swiftly down a steep gradient.It cuts downwards, forming V-shaped valleys and waterfalls.A levee and a delta form in the lower course.A meander typically forms in the middle course.Therefore, the feature associated with the upper course is a waterfall.Answer:D. Waterfall