The correct option is D i - c
ii - a
iii - b
The journey of a river has three stages: youthful, mature, and old stage. These stages are also called the upper course, the middle course, and the lower course. In its youthful stage or in the upper course, the river is full of energy and power. In the mature stage of the river, the flow is relatively slower than in the youthful stage. The river flows very slowly and calmly in the old stage.