B.O.D. test is made for measuring

Options

A. air pollution
B. water pollution
C. noise pollution
D. soil pollution

Explanation

**Step-by-Step Solution:**

1. **Understanding B.O.D.**: B.O.D. 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. **Purpose of B.O.D. Test**: The B.O.D. test is specifically designed to assess the level of organic pollution in water. It indicates how much oxygen is required by bacteria to break down organic material in a water sample.

3. **Aerobic Conditions**: The test is conducted under aerobic conditions, meaning that it measures the oxygen consumption by microorganisms in the presence of oxygen.

4. **Measurement of Pollution**: By measuring the B.O.D., we can determine the degree of water pollution. A higher B.O.D. value indicates a higher level of organic pollutants in the water.

5. **Normal vs. Polluted Water**: Typically, clean water has a B.O.D. value of around 5 parts per million (ppm). In contrast, polluted water may have a B.O.D. value significantly higher, often around 10 ppm or more.

6. **Conclusion**: Therefore, the B.O.D. test is primarily used for measuring water pollution.

**Final Answer**: The B.O.D. test is made for measuring **water pollution**.

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