What is BOD?

Options

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

Answer

### Step-by-Step Solution:

1. **Definition of BOD**:
- BOD stands for Biological Oxygen Demand. It is a measure of the amount of dissolved oxygen required by aerobic microorganisms to decompose organic matter present in water.

2. **Understanding the Concept**:
- In simpler terms, BOD indicates how much oxygen is needed by bacteria and other microorganisms to break down organic materials in a water sample. This process occurs through oxidation.

3. **Importance of BOD**:
- BOD is an important parameter in assessing water quality. High BOD levels indicate a high amount of organic matter in the water, which can lead to oxygen depletion and negatively impact aquatic life.

4. **Options Analysis**:
- The question provides multiple-choice options regarding the definition of BOD:
- A) The amount of O2 utilized by organisms in water
- B) The amount of O2 utilized by microorganisms for decomposition
- C) The total amount of O2 present in water
- D) All of the above
- The correct answer is **B**, as it specifically refers to the oxygen used by microorganisms for the decomposition of organic matter.

5. **Conclusion**:
- Therefore, BOD is a critical environmental indicator that helps in understanding the level of pollution in water bodies and the health of aquatic ecosystems.