Final answer:
Young rivers carry large objects due to their fast flow and narrow channels. Mature rivers carry medium-sized objects as their energy decreases with a milder slope. Old rivers create many meanders as they slow down and flow through wide valleys.
Step-by-step explanation:
The best descriptions for the types of rivers based on their stages of development are as follows:
- Young rivers: Carry large objects - Due to their steep gradients, fast flow, and narrow channels, young rivers have the energy to carry larger debris and sediment.
- Mature rivers: Carry medium-sized objects - As rivers age, their gradients decrease, causing them to slow down and become less able to carry the largest debris but still capable of transporting medium-sized materials.
- Old rivers: Have many meanders - In the final stage of their lifecycle, old rivers have a very gentle gradient and move slowly through wide, flat valleys, often resulting in a winding, meandering course.