The compressed air used by sea divers comprises:

Options

A. `He,N_(2),O_(2)`
B. `N_(2),He`
C. `O_(2),N_(2)`
D. `He,O_(2)`

Explanation

To answer the question regarding the composition of compressed air used by sea divers, we need to analyze the gases that are typically utilized in diving situations.

### Step-by-Step Solution:

1. **Understanding the Composition of Compressed Air**:
- Compressed air is primarily made up of nitrogen (N₂) and oxygen (O₂). However, for deep-sea diving, the composition may vary to prevent nitrogen narcosis and other issues associated with high-pressure environments.

2. **Identifying the Gases Used in Diving**:
- In addition to nitrogen and oxygen, helium (He) is often used in diving mixtures, especially for deep dives. Helium is less soluble in blood compared to nitrogen, which reduces the risk of decompression sickness (the bends).

3. **Analyzing the Benefits of Helium**:
- Helium is preferred because it is less narcotic than nitrogen and does not cause as much discomfort to divers. This allows divers to operate more effectively at greater depths.

4. **Conclusion**:
- The typical gases used in compressed air for divers include helium and oxygen, particularly in deeper dives where reducing nitrogen levels is crucial for safety.

### Final Answer:
The compressed air used by sea divers comprises **Helium and Oxygen**.

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