Which of these are biodegradable pollutants?
(i) Pesticides (ii) Mercuric salts
(iii) Sewage (iv) Radioactive wastes

Options

A. (i) and (ii)
B. (i) and (iii)
C. (i), (iii) and (iv)
D. (iii) only

Explanation

To determine which of the listed pollutants are biodegradable, we need to analyze each option based on the definition of biodegradable pollutants. Biodegradable pollutants are substances that can be broken down into simpler, non-toxic substances by the action of microorganisms, such as bacteria.

### Step-by-Step Solution:

1. **Identify the options**: The options provided are:
- (i) Pesticides
- (ii) Mercuric salts
- (iii) Sewage
- (iv) Radioactive wastes

2. **Analyze each option**:
- **(i) Pesticides**: Pesticides are chemicals used to kill pests. Many pesticides are synthetic and do not decompose easily. They often remain in the environment for extended periods, making them non-biodegradable.
- **(ii) Mercuric salts**: These are inorganic compounds containing mercury. They are highly toxic and do not decompose, thus classified as non-biodegradable.
- **(iii) Sewage**: Sewage is organic waste that can be broken down by microorganisms. Therefore, sewage is considered a biodegradable pollutant.
- **(iv) Radioactive wastes**: These are byproducts of nuclear reactions and contain radioactive materials that can remain hazardous for thousands of years. They do not decompose and are classified as non-biodegradable.

3. **Conclusion**: Among the options, the only biodegradable pollutant is **(iii) Sewage**.

### Final Answer:
The biodegradable pollutant from the given options is **(iii) Sewage**.

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