The correct answer is: A. Rocky stage.
Meandering is a process of a river’s course changing direction over time. It is caused by the erosion of the river’s banks by the water flowing over them. The water erodes the banks more on the outside of a curve than on the inside, which causes the river to bend more and more. Eventually, the river may cut through the neck of
a meander, creating an oxbow lake.The rocky stage is the first stage in the development of a river. In this stage, the river is still young and has a lot of energy. The water flows quickly and erodes the banks of the river, causing it to meander.
The other options are incorrect because they are not stages in the development of a river. The delta stage is the final stage in the development of a river. In this stage, the river has deposited all of its sediment and has formed a delta. The boulder stage is a stage in the development of a river when the river is carrying a lot of boulders. The trough stage is a stage in the development of a river when the river is flowing through a valley.