A feature commonly found in the youthful stage of a river is

Step 1: Analyze the question The question asks which feature is typical of the youthful (upper) stage of a river.

Step 2: Concept: stages of a river

• Youthful (upper) stage: The river flows down steep slopes with high speed and strong vertical erosion (downcutting). This produces V-shaped valleys, waterfalls, rapids, gorges, potholes, and interlocking spurs.
• Mature (middle) stage: Lateral erosion becomes more important. Meanders begin to develop, and the valley widens.
• Old (lower) stage: The river flows slowly over a flat plain and deposits material. This produces floodplains, levees, ox-bow lakes, braided channels, and deltas.

Step 3: Check each option

• A. Levee: Built by deposition during floods on the lower course. Old stage.
• B. Meander: Typical of the middle and lower courses, where lateral erosion dominates. Not youthful.
• C. Ox-bow lake: Forms when a meander is cut off. Old stage.
• D. Interlocking spurs: In the upper course, the river is too weak to erode sideways, so it winds around ridges of hill that overlap like the teeth of a zip. This is a youthful feature.

Step 4: Answer Interlocking spurs are formed in the youthful stage, so the answer is D.

Tip: Remember "Upper = Up-and-down erosion": V-shaped valleys, waterfalls, rapids, gorges, and interlocking spurs. "Lower = Layers of deposits": levees, floodplains, ox-bow lakes, and deltas.