What is BOD ?

Options

A. The amount of `O_(2)` utilized by organisms in water
B. The amount of `O_(2)` utilized by micro-organisms for decomposition
C. The total amount of `CO_(2)` present in water
D. All of the above

Answer

**Step-by-Step Solution:**

1. **Understanding BOD**: BOD stands for Biochemical Oxygen Demand. It is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water.

2. **Definition**: BOD specifically refers to the amount of dissolved oxygen (O2) that is required by aerobic biological organisms to break down organic materials in a water sample.

3. **Importance of BOD**: BOD is crucial for assessing the health of a water body. A high BOD indicates a high level of organic pollution, which can lead to oxygen depletion and harm aquatic life.

4. **Key Components**:
- BOD measures the oxygen demand of aerobic microorganisms.
- It is determined over a specific time period and at a certain temperature.

5. **Identifying the Correct Option**:
- The options provided include:
1. The amount of oxygen utilized by organisms in water.
2. The amount of oxygen utilized by microorganisms for decomposition.
3. The total amount of carbon dioxide present in water.
4. All of the above.
- The most accurate definition of BOD is the second option: "the amount of oxygen utilized by microorganisms for decomposition."

6. **Conclusion**: Therefore, the answer to the question "What is BOD?" is the second option.

**Final Answer**: The amount of oxygen utilized by microorganisms for decomposition.

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