The correct answer is D. All of the above.
Meandering is a process by which a stream or river flows in a winding course. It is caused by a combination of factors, including the sediment load of the stream, the discharge and hydraulic properties of the stream, and the relative erodibility of the bed and banks.
The sediment load of a stream is the amount of sediment that it carries. The more sediment a stream carries, the more likely it is to meander. This is because the sediment acts as a buffer between the stream and the bed and banks, reducing the friction between the two and allowing the stream to flow more easily.
The discharge of a stream is the volume of water that it flows per unit time. The higher the discharge, the more likely it is for a stream to meander. This is because the higher discharge creates more energy, which can be used to erode the bed and banks of the stream.
The hydraulic properties of a stream are the factors that affect the flow of water in the stream, such as the slope of the bed, the width of the channel, and the roughness of the bed and banks. The hydraulic properties of a stream can affect the way that the stream meanders. For example, a stream with a steep slope is more likely to meander than a stream with a gentle slope.
The relative erodibility of the bed and banks of a stream is the difference in the resistance of the bed and banks to erosion. The more erodible the bed and banks, the more likely it is for the stream to meander. This is because the erodible bed and banks can be easily eroded by the stream, which can cause the stream to change course.
In conclusion, the process of meandering is due to a combination of factors, including the sediment load of the stream, the discharge and hydraulic properties of the stream, and the relative erodibility of the bed and banks.