Measurement of rate of oxygen utillsation by a unit volume of water over a period of time is to measure.:

Options

A. Fermentation
B. Biogas generation
C. Biosynthetic pathway
D. Biological oxygen demand

Answer

To solve the question regarding the measurement of the rate of oxygen utilization by a unit volume of water over a period of time, we need to analyze the options provided and understand the concepts related to each.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about measuring the rate of oxygen utilization in water over time. This typically involves assessing how much oxygen is consumed by microorganisms in a given volume of water.

2. **Evaluating the Options**:
- **Option 1: Fermentation**: This process occurs in the absence of oxygen (anaerobic conditions) where organic substances are broken down. Since the question refers to oxygen utilization, fermentation is not applicable here.
- **Option 2: Biogas Regeneration**: This process also occurs anaerobically and involves the production of biogas from organic matter. Since it does not involve oxygen utilization, this option is incorrect.
- **Option 3: Biosynthetic Pathway**: This refers to the metabolic pathways that construct molecules from smaller units. While it may involve oxygen, it does not specifically measure oxygen utilization in the context of water and microorganisms.
- **Option 4: Biological Oxygen Demand (BOD)**: This is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. It directly relates to the question as it quantifies oxygen utilization over time.

3. **Conclusion**: Based on the evaluation, the correct answer is **Option 4: Biological Oxygen Demand (BOD)**. This option accurately describes the measurement of oxygen utilization by bacteria in a unit volume of water over a specified period.

### Final Answer:
The measurement of the rate of oxygen utilization by a unit volume of water over a period of time is to measure **Biological Oxygen Demand (BOD)**.

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