The excessive use of one of the following in agriculture can cause the death of fish in a pond by oxygen starvation. This one is:
  1. fertilizers
  2. manures
  3. pesticides
  4. herbicides

Correct Answer: A. fertilizers 

Explanation: The fertilizers act as nutrients for the algae to grow. When these algae die, they act as a nutrient for decomposers like bacteria. As a result of this process, a lot of oxygen in the water gets used up and leads to the deficiency of oxygen in the water. This may kill the aquatic organisms.


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