Which of the following sources of water is not used for drinking purpose due to dissolved salts present in them?

Options

A. Rain water
B. Sea water
C. Spring water
D. River water

Explanation

To determine which source of water is not used for drinking purposes due to the presence of dissolved salts, we can analyze the different sources of water mentioned in the question.

### Step-by-Step Solution:

1. **Identify the Sources of Water**:
- The sources mentioned are rainwater, sea water, and river water.

2. **Analyze Rainwater**:
- Rainwater is collected from precipitation. It typically does not contain dissolved salts because it is formed from the condensation of water vapor in the atmosphere. Thus, rainwater is generally safe for drinking.

3. **Analyze Sea Water**:
- Sea water is the water found in oceans and seas. It is known to contain a high concentration of dissolved salts, primarily sodium chloride (common salt). Due to this high salinity, sea water is not suitable for drinking.

4. **Analyze River Water**:
- River water is fresh water that flows in rivers. While it can contain some dissolved minerals, it generally has a much lower concentration of salts compared to sea water. Therefore, river water is often used for drinking after proper treatment.

5. **Conclusion**:
- Among the sources analyzed, sea water is the one that is not used for drinking purposes due to the high levels of dissolved salts present in it.

### Final Answer:
**Sea water is not used for drinking purposes due to the dissolved salts present in it.**

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