Which of the following pairs are associated with the upper course of a river? I. Deltas II. Gorges III. Meanders IV. Rapids

Deltas are landforms formed at the mouth of a river where it meets an ocean, sea, or lake. Therefore, they are not associated with the upper course of a river. Meanders are bends or curves in a river channel that form as the water flows. While they can occur in any part of a river, they are most commonly found in the middle and lower courses. Therefore, they are not associated with the upper course of a river. Rapids are sections of a river where the water flows rapidly over rocks or a steep gradient, creating turbulence and white water. They are typically found in the upper course of a river, where the gradient is steeper and the water flows faster. Gorges are narrow, steep-sided valleys that form as a river cuts through hard rock. They are also commonly found in the upper course of a river, where the gradient is steeper and the river is more erosive. Therefore, the pair associated with the upper course of a river are II and IV, which correspond to gorges and rapids, respectively.