Concept:In the old stage of a river, the lower course has a gentle gradient and deposits sediment, forming features like meanders.
Explanation:The lower section of a river flows over a flat landscape, so its erosive power is reduced.
As a result, the river develops large, sweeping bends called meanders.
Meanders are typical features of the old stage of a river.
Features such as spurs and potholes belong to the youthful stage, while levees are formed on floodplains but are less diagnostic of old age than meanders.
Thus, the presence of a meander indicates that R. Kam is in its old stage.
Answer:D. meander
