Richest source of bacteria is :-

Options

A. Air
B. Soil
C. Water
D. Milk

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the richest source of bacteria among the given options: air, soil, water, and milk.

2. **Analyzing Each Option**:
- **Air**: While bacteria can be found in the air, their concentration is relatively low compared to other sources.
- **Water**: Bacteria are present in water, but again, the concentration is not as high as in soil.
- **Milk**: Milk can contain bacteria, but it does not have as high a concentration as soil.
- **Soil**: Soil is known to be a rich habitat for bacteria. In fact, it is estimated that there are about 1 to 1.5 million bacteria in just 1 gram of soil.

3. **Conclusion**: Based on the analysis, the richest source of bacteria is soil, as it has the highest concentration of bacteria compared to the other options.

4. **Final Answer**: The correct answer is **soil**.

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