**Step-by-Step Solution:**
1. **Understanding the Question**: The question asks for the meaning of the acronym "BOD".
2. **Identifying the Full Form**: The full form of BOD is "Biological Oxygen Demand".
3. **Explaining the Concept**: BOD is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. It indicates the level of organic pollution in the water.
4. **Analyzing the Options**:
- Option A: Biological Optimal Demand - This is incorrect.
- Option B: Biological Optimal Decide - This is also incorrect.
- Option C: None of the above - This is the correct answer since neither of the first two options represents the full form of BOD.
5. **Conclusion**: The correct answer is Option C: None of the above.
**Step-by-Step Solution:**
1. **Understanding the Question**: The question asks for the meaning of the acronym "BOD".
2. **Identifying the Full Form**: The full form of BOD is "Biological Oxygen Demand".
3. **Explaining the Concept**: BOD is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. It indicates the level of organic pollution in the water.
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