The correct answer is C. Degrading type.
A deficit of sediments in flowing water may cause a river to degrade, or become deeper and narrower. This is because the river will no longer have enough sediment to deposit on its banks, and the current will be able to erode the banks more easily. This can lead to the river becoming unstable and changing course more frequently.
Option A, meandering type, is incorrect because a meandering river is one that has a winding course. This is caused by the river depositing sediment on the outside of its bends and eroding sediment on the inside of its bends. A deficit of sediments would not cause a river to meander more.
Option B, aggrading type, is incorrect because an aggrading river is one that is building up its bed. This is caused by the river depositing more sediment than it is eroding. A deficit of sediments would not cause a river to aggrade more.
Option D, sub-critical type, is incorrect because a sub-critical river is one that is flowing at a slower speed than the critical speed. This is caused by the river having a wider and shallower channel. A deficit of sediments would not cause a river to flow more slowly.