What are the two types of sound-powered telephones?

The correct answer identifies the two types of sound-powered telephones as handset and headset. Handset sound-powered telephones are designed for individual use with a microphone and speaker integrated into one component. They allow users to hold the phone to their ear and speak directly into it, which is typically more straightforward and user-friendly in most scenarios.

Headset sound-powered telephones, on the other hand, feature separate earphones and a microphone, allowing for hands-free operation. This setup is particularly useful in situations where the operator needs to maintain mobility or use both hands for other tasks while communicating.

These classifications are crucial because they cater to different operational needs and preferences in communication, especially in environments where traditional electrical power may not be available. Other options, such as wireless and wired, don't specifically address the sound-powered feature. Instead, they pertain to the connection method of telephones rather than their fundamental design based on user interaction.