The correct answer is D. I., II., III., And IV. All the options are true.
The process is systematic and all the answers contribute to the same problem.
I. Erosion introduces pesticides and toxins into waterways, causing pollution.
Soils eroded due to agricultural exploitation carry pesticides, fertilizers and heavy metals that are introduced into the waterways and causing their contamination.
II. Polluted waterways decrease biodiversity.
The water of the waterways, being contaminated, intoxicates fish, plants and other living beings that in turn many of them are eaten by other living beings that can also suffer intoxication.
III. Eroded soil allows sediment to break off and clog waterways.
The lack of trees and the loss of soil properties do not allow the absolution of rainwater. Much land is carried by the wind in the form of dust and it ends up being deposited in waterways and another part of the earth is carried by rainwater to streams and rivers that end up with levels of sedimentation higher than desirable, and by gravity this sedimentation is deposited in the bottom of the waterways and finally obstructs causing flooding in large territories.
IV. Eroded soil becomes useless for agriculture.
Both flooded territories and lands whose river beds are polluted or simply eroded by imbalances in agricultural activity, become unusable land for agriculture or land with low agricultural productivity.
