In its old stage, a river would I. be interrupted by waterfalls and rapids II. flow sluggishly and develop…

Analyze the question: It asks which features belong to the old stage (lower course) of a river.

Concept: A river has three stages.

• Youthful (upper course): The river has steep gradient and high energy, and it erodes vertically. Features are V-shaped valleys, interlocking/truncated spurs, waterfalls, rapids and gorges.
• Mature (middle course): The river flows more gently, erodes laterally, and the valley widens. Features are the beginnings of meanders and tributaries joining.
• Old (lower course): The gradient is very gentle, the river flows slowly, and it deposits more than it erodes. Features are pronounced meanders, ox-bow lakes, a wide flood plain, levees and deltas.

Check each statement:

• I. Interrupted by waterfalls and rapids: These occur in the youthful stage, where hard and soft rocks alternate on a steep slope. ✗
• II. Flows sluggishly and develops pronounced meanders: This is typical of the old stage, with its low gradient and lateral erosion. ✓
• III. Flows fast and has truncated spurs: These are upper-course features, formed by vigorous erosion. ✗
• IV. Develops levees and a flood plain: These come from deposition during floods in the lower course. ✓

So the correct statements are II and IV only.

Exam tip: Match the stage to the process. Old stage means slow, depositing, so look for meanders, ox-bow lakes, levees, flood plains and deltas. Youthful stage means fast, eroding, so look for waterfalls, rapids, gorges, V-shaped valleys and truncated spurs.