Wave which cannot travel in vacumm is

Options

A. X-rays
B. infrasonic
C. ultraviolet
D. radio waves

Explanation

To solve the question "Wave which cannot travel in vacuum is," we need to analyze the types of waves mentioned in the options provided. The options are x-ray, infrasonic, ultraviolet, and radio waves.

### Step-by-Step Solution:

1. **Identify the Types of Waves**:
- **X-ray**: This is an electromagnetic wave.
- **Ultraviolet**: This is also an electromagnetic wave.
- **Radio Waves**: These are electromagnetic waves as well.
- **Infrasonic**: This refers to sound waves with frequencies below the audible range.

2. **Understanding Electromagnetic Waves**:
- Electromagnetic waves (like x-rays, ultraviolet, and radio waves) can travel through a vacuum. They do not require a medium to propagate and travel at the speed of light (approximately \(3 \times 10^8\) m/s).

3. **Understanding Mechanical Waves**:
- Mechanical waves, such as sound waves (including infrasonic waves), require a medium (solid, liquid, or gas) to travel. They cannot propagate in a vacuum.

4. **Conclusion**:
- Since x-rays, ultraviolet, and radio waves are all electromagnetic waves and can travel in a vacuum, the only wave that cannot travel in a vacuum is the infrasonic wave.

Thus, the correct answer to the question is **infrasonic waves**.

### Final Answer:
**Infrasonic waves cannot travel in a vacuum.**

---