How has agriculture contributed to the decline of the Chang Jiang's water quality?\

the fertilizers used by farmers contaminate the river.

Explanation: agriculture contributed to the decline of the Chang Jiang's  water quality because of the fertilizers used by farmers contaminated the river. Agricultural activities really affected the people’s environment, though agriculture is very important in the society, it makes food available for the people. However, it affected the River by contaminating it due to the fertilizers used by the farmers.

the correct answer on edgen is:

(c.) prevent the spread of communism.

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