Sound travels in the form of ......

Options

A. compression and rarefactions
B. crest
C. trough
D. all of the above

Answer

To answer the question "Sound travels in the form of...", let's break down the solution step by step.

### Step-by-Step Solution:

1. **Understanding Sound as a Wave**:
- Sound is a type of energy that travels through a medium (like air, water, or solids) in the form of waves.

**Hint**: Remember that sound requires a medium to travel; it cannot travel through a vacuum.

2. **Identifying the Type of Wave**:
- The specific type of wave that sound travels as is known as a longitudinal wave. In longitudinal waves, the particles of the medium move parallel to the direction of the wave's propagation.

**Hint**: Think about how a slinky moves when you push and pull it; the coils move back and forth in the same direction as the wave travels.

3. **Understanding Compression and Rarefaction**:
- In a longitudinal wave, there are areas where particles are close together, known as compressions, and areas where particles are spread apart, known as rarefactions.

**Hint**: Visualize a slinky again; when you compress it, you create areas of high density (compression) and when you let it go, you create areas of low density (rarefaction).

4. **Conclusion**:
- Therefore, sound travels in the form of compressions and rarefactions, which are characteristics of longitudinal waves.

**Hint**: Remember that the correct answer is specifically about the nature of sound waves, not other types of waves like transverse waves (which have crests and troughs).

### Final Answer:
Sound travels in the form of compressions and rarefactions.