Explanation:
Erosion by a river is caused by its capacity to curve out rocks and carry soil particles as sediments due to its erosion power. Rivers carve out rocks to form the pebbles you see in a river and also the rapids and cataracts.
A river contributes to the weathering of rocks such as limestone rocks. The water dissolves the calcium carbonate minerals in the limestone rocks making it brittle and easily crumble. Water also causes ferrous rocks to easily crumble due to turning of the iron minerals into rust.
rivers deposit their sediments when their velocity decreases. Deposits by rivers cause features like oxbow lakes and deltas that are observed at the mouth of rivers, where the slope gradient is very low.
The soviet Union is primarily responsible for the pollution in the region of Central Asia. The correct option among all the options that are given in the question is the first option. The Soviet Union is one country that depends highly on coal based electricity generation. These power stations release toxic gases that are a reason for global warming.
The answer is seafloor spreading and subduction.
Hope this ain't too late (this is the PLATO answer)