The erosional work of a river is related to what?

Correct answer: Cutting rocks and soil

The direct answer is A: cutting rocks and soil. River erosion is the wearing away and removal of material by flowing water. In a river’s upper course, the slope is usually steep, so water flows quickly and has strong cutting force. Step by step: rain and melting snow add water; the water flows downhill; fast flow strikes the bed and banks; loose soil and pieces of rock are loosened and carried away. Therefore erosion is related to cutting rocks and soil. Option A is correct. Option B is wrong because planting trees is an activity of people or vegetation, not the erosional work of a river. Option C is wrong because rivers do not stop rainfall; rain is one source of river water. Option D is wrong because making air is not a river process. A river may also transport and deposit sediment, but those are different actions from erosion. Deposition occurs when the river loses speed and drops material. The memory cue is: erosion cuts, transportation carries, and deposition drops; the upper course is especially associated with strong erosion.