Answer :The correct answer is 3) Increased nitrates and phosphates level.
Chemical fertilizer :
These are substances that are applied into soil or directly to plants to provide them optimal nutrition for their growth and development . These are also known as synthetic fertilizers.
These chemical fertilizers contain Nitrogen as nitrates , phosphorous as phosphates and potassium as salt of it .
Example : Urea . ammonium nitrate etc .
When these chemical fertilizers are sprinkled over plants or given to soil , during rain , they enter water bodies through runoff and contaminate them .
Due to which the nitrates and phosphates enters water bodies and cause Eutrophication . Eutrophication causes excessive growth of algae which in turn causes oxygen deficient in water bodies .
This is how fertilizer pollute the water bodies by increasing the level of nitrates and phosphates .
Hence option 3) Increases nitrates and phosphates level is correct answer .