High biological oxygen demand in a water body means ……….
(a) water is not polluted
(b) water is less polluted
(c) water body contains lots of life forms and organic pollutant.
(d) None of the above

Options

A. water is not polluted
B. water is less polluted
C. water body contains lots of life forms and organic pollutant.
D. None of the above

Answer

To solve the question regarding high biological oxygen demand (BOD) in a water body, we need to understand what BOD signifies and its implications for water quality.

### Step-by-Step Solution:

1. **Understanding BOD**: Biological Oxygen Demand (BOD) refers to the amount of oxygen that microorganisms will consume while decomposing organic matter in water. A high BOD indicates that there is a significant amount of organic material present that is being broken down by these microorganisms.

2. **Implications of High BOD**: When BOD is high, it suggests that there is a large quantity of organic pollutants in the water. This means that the microorganisms are actively consuming oxygen to decompose this organic matter.

3. **Effects on Dissolved Oxygen**: As the microorganisms consume oxygen, the levels of dissolved oxygen (DO) in the water decrease. This can lead to a situation where there is insufficient oxygen for other aquatic life forms, potentially harming or killing them.

4. **Analyzing the Options**:
- **(a) Water is not polluted**: This is incorrect because a high BOD indicates pollution.
- **(b) Water is less polluted**: This is also incorrect; high BOD means more pollution.
- **(c) Water body contains lots of life forms and organic pollutant**: This is correct, as high BOD indicates a lot of organic matter being decomposed, which supports microbial life.
- **(d) None of the above**: This is incorrect since option (c) is true.

5. **Conclusion**: The correct answer is (c) "water body contains lots of life forms and organic pollutant."

### Final Answer:
(c) water body contains lots of life forms and organic pollutant.

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