Which of the following is an elastic wave?

Options

A. Sound waves
B. Light waves
C. X-rays
D. Radio waves

Explanation

To determine which of the given options is an elastic wave, we need to analyze the characteristics of each type of wave mentioned: sound waves, light waves, x-rays, and radio waves.

### Step-by-Step Solution:

1. **Understanding Elastic Waves**:
- Elastic waves are defined as waves that require a material medium for their propagation. This is because they rely on the elastic properties of the medium, which allow the wave to travel through it.

2. **Identifying the Options**:
- The options provided are:
- Sound waves
- Light waves
- X-rays
- Radio waves

3. **Analyzing Sound Waves**:
- Sound waves are mechanical waves that require a medium (solid, liquid, or gas) to travel. They cannot propagate through a vacuum. This means they depend on the elasticity of the medium, making them elastic waves.

4. **Analyzing Light Waves**:
- Light waves are electromagnetic waves that do not require a medium for propagation. They can travel through a vacuum, which means they are not elastic waves.

5. **Analyzing X-rays**:
- X-rays are also electromagnetic waves and, like light waves, do not require a medium for propagation. Thus, they are not elastic waves.

6. **Analyzing Radio Waves**:
- Radio waves are another form of electromagnetic waves that can travel through a vacuum. Therefore, they are not elastic waves.

7. **Conclusion**:
- Among the options provided, only sound waves require a material medium for propagation and depend on the elastic properties of that medium. Therefore, sound waves are classified as elastic waves.

### Final Answer:
The elastic wave among the given options is **sound waves**.

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