Sound cannot travel in :

Options

A. gases
B. liquids
C. solids
D. vacuum

Answer

**Step-by-Step Solution:**

1. **Understanding Sound:** Sound is a form of energy that is produced by vibrations. These vibrations create waves that travel through different mediums.

2. **Identifying the Mediums:** There are three primary types of mediums through which sound can travel:
- **Gases:** Sound can travel through gases like air.
- **Liquids:** Sound can also travel through liquids such as water.
- **Solids:** Sound can travel through solids like metal or wood.

3. **The Concept of Vacuum:** A vacuum is a space that is devoid of matter, meaning it has no particles (no gases, liquids, or solids).

4. **Why Sound Cannot Travel in Vacuum:** Since sound requires a medium to propagate (to move through), and a vacuum has no particles to vibrate, sound cannot travel in a vacuum.

5. **Conclusion:** Therefore, the correct answer to the question "Sound cannot travel in:" is **vacuum**.

---