dB is a standard abbreviation used for the quantitaive expression of :

Options

A. A certain pesticide
B. The density of bacteria in a medium
C. A particular pollutant
D. The dominant Bacillus in a culture

Answer

**Step-by-Step Solution:**

1. **Understanding the Context of dB**: The abbreviation "dB" stands for decibel, which is a unit used to measure sound levels. It quantifies the intensity of sound and is commonly used in various fields, including environmental science, to assess noise pollution.

2. **Identifying the Options**: The question provides four options related to what dB quantifies:
- A certain pesticide
- The density of bacteria in a medium
- A particular pollutant
- The dominant bacillus in a culture

3. **Analyzing Each Option**:
- **A certain pesticide**: This option is incorrect because pesticides are not measured in decibels.
- **The density of bacteria in a medium**: This option is also incorrect as bacterial density is typically measured in colony-forming units (CFU) or similar units, not in decibels.
- **A particular pollutant**: This option is correct because noise pollution, which is quantified in decibels, is a type of pollutant.
- **The dominant bacillus in a culture**: This option is incorrect since the identification of bacterial species does not involve decibel measurements.

4. **Conclusion**: After analyzing all options, the correct answer to the question is that dB is a standard abbreviation used for the quantitative expression of "a particular pollutant," specifically referring to noise pollution.

**Final Answer**: The correct option is **c) a particular pollutant**.

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