What type of raceway is described as unthreaded and thin-walled, suitable for protecting conductors?

The correct type of raceway described as unthreaded and thin-walled, suitable for protecting conductors, is EMT, which stands for Electrical Metallic Tubing. EMT is typically used for indoor applications where environmental conditions are not severe. Its lightweight and thin-walled design make it easier to handle and install compared to other types of conduit.

Additionally, EMT provides a good balance of strength and flexibility, allowing for easier adjustments during installation. It is also commonly used in commercial and residential buildings because it can be easily coupled and bent without needing specialized tools, simplifying the installation process. This type of raceway is designed to protect conductors from physical damage and also facilitates grounding when installed properly, making it an effective choice for many electrical applications.