BOD is measure of

Options

A. Extent of pollution with organic compounds
B. Oxygen required by green plants during night
C. CO combined in blood
D. none of these

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. **Analyzing the Options**:
- **Option 1**: "Extend of pollution with organic compounds" - This relates directly to BOD, as higher BOD indicates more organic pollution.
- **Option 2**: "Oxygen required by green plants during night" - This is not related to BOD, as it pertains to plant respiration.
- **Option 3**: "CO combined in blood" - This refers to carbon dioxide and is unrelated to BOD.
- **Option 4**: "None of these" - This option can be eliminated since the first option is correct.

3. **Conclusion**: Based on the analysis, the correct answer is the first option: "Extend of pollution with organic compounds". Higher BOD levels indicate a higher level of organic pollution in the water.

4. **Explanation of BOD**: When organic matter is present in water, microorganisms use dissolved oxygen to break it down. The more organic matter there is, the higher the BOD, which can lead to lower oxygen levels in the water, affecting aquatic life.

**Final Answer**: BOD is a measure of the extent of pollution with organic compounds.

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