What are some examples of audio surveillance?

The correct answers are C. listening devices and D. phone taps.

Listening devices are specifically designed to capture audio and can be hidden in various environments. Phone taps refer to the interception of phone conversations for monitoring purposes, often used in law enforcement.

On the other hand, hidden cameras (A) focus on visual surveillance, and fitness wristbands (B) track physical activity rather than audio.

If you have more questions or need further clarification, feel free to ask!