Given below are two statements:
Statement I: In polluted water values of both dissolved oxygen and BOD are very low.
Statement II: Eutrophication results in decrease in the amount of dissolved oxygen.
In the light of the above statements, choose the most appropriate answer from the options given below:

We need to evaluate both statements about water pollution.

Statement I: "In polluted water, values of both dissolved oxygen and BOD are very low."

Polluted water contains a large amount of organic matter. Microorganisms consume dissolved oxygen to decompose this organic matter. Therefore:

• Dissolved oxygen (DO) is low in polluted water — this part is correct.
• Biochemical Oxygen Demand (BOD) is high in polluted water, because a large quantity of oxygen is needed to break down the organic waste — this part is incorrect.

So Statement I is false.

Statement II: "Eutrophication results in decrease in the amount of dissolved oxygen."

Eutrophication is the excessive growth of algae and aquatic plants due to nutrient enrichment (phosphates, nitrates). When these organisms die, their decomposition by bacteria consumes large amounts of dissolved oxygen, leading to oxygen depletion in the water body.

So Statement II is true.

Therefore, the correct answer is Option D: Statement I is false but Statement II is true.