As they multiply, die and decompose, algae deplete the ocean’s surface layers of oxygen. Often, the large amounts of farm fertilizer that run from fields into the rivers cause algae populations to explode. The MOST LIKELY result is that
A) sedimentation increases.
B) sedimentation decreases.
C) fish populations decrease.
D) fish populations increase.

C) fish populations decrease

Explanation:

Depletion of algae and increase in the population of algae due to fertilizers have harmful effect on fish or other water popuation.

The algae or algal bloom blocks the sunlight to reach other organisms, causes depletion in the oxygen level in water and secreting toxins into the water that allows deacrease in the fish population.

Hence, the correct option is C.

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