Biochemical oxygen demand measures:

Options

A. Industrial pollution
B. Air pollution
C. Dissolved oxygen required for decomposers
D. Pollution capacity of effluents

Answer

**Step-by-Step Solution:**

1. **Understanding Biochemical Oxygen Demand (BOD):**
- Biochemical Oxygen Demand (BOD) is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. It is an important indicator of water quality.

2. **Identifying What BOD Measures:**
- BOD specifically measures the oxygen required for the decomposition of organic matter in a given volume of water (usually 1 liter). The higher the BOD value, the more polluted the water is, as it indicates a higher concentration of organic matter.

3. **Analyzing the Options:**
- The question provides several options:
a) Industrial pollution
b) Air pollution
c) Dissolved oxygen required for decomposers
d) Pollution capacity of effluents

4. **Evaluating Each Option:**
- **Option a (Industrial pollution):** While BOD can be influenced by industrial discharges, it does not directly measure industrial pollution.
- **Option b (Air pollution):** BOD is not a measure of air pollution; it is related to water quality.
- **Option c (Dissolved oxygen required for decomposers):** This option aligns with the definition of BOD, as it measures the oxygen needed for decomposers to break down organic matter.
- **Option d (Pollution capacity of effluents):** While BOD can indicate the pollution capacity of effluents, it does not directly measure it.

5. **Conclusion:**
- The correct answer is **Option c: Dissolved oxygen required for decomposers**. This option accurately reflects what BOD measures.