Concept:The youthful stage of a river is dominated by vertical erosion and typical landforms such as interlocking spurs.
Explanation:In this early stage, the river flows swiftly down a steep slope and cuts downward into its channel.
Because the river lacks the energy to erode sideways, it takes a winding path around resistant rocks on the valley sides.
This winding around hard rock masses creates finger-like projections that overlap one another, called interlocking spurs.
Features like levees, meanders, and ox-bow lakes develop later when the river begins to erode laterally in its mature or old stage.
Therefore, among the given options, only interlocking spurs belong to the youthful stage.
Answer:D. Interlocking spurs