What do dolphins, bats and porpoise use

Options

A. Ultrasound
B. Infrasound
C. Both (A) and (B)
D. None of them

Explanation

### Step-by-Step Solution:

1. **Identify the Animals**: The question asks about dolphins, bats, and porpoises.
- These animals are known for their unique communication and navigation methods.

2. **Understanding Sound Types**: The options provided are ultrasound, infrasound, both A and B, or none of them.
- **Ultrasound**: Sound waves that have frequencies higher than the upper audible limit of human hearing (above 20 kHz).
- **Infrasound**: Sound waves that have frequencies lower than the lower audible limit of human hearing (below 20 Hz).

3. **Research the Sound Usage**:
- Dolphins, bats, and porpoises are known to use **ultrasound** for navigation and communication.
- They emit sound waves and listen for the echoes that bounce back from objects, which helps them identify locations and objects in their environment.

4. **Conclusion**: Since dolphins, bats, and porpoises primarily use ultrasound, the correct answer is **ultrasound**.

### Final Answer:
Dolphins, bats, and porpoises use **ultrasound**.

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