Which component is described as providing stability and support for a mounted luminaire in the text?

The T-type conduit body is specifically designed to provide stability and support for mounted luminaires. It acts as both a junction box and a means to securely anchor the conduit connections, ensuring that electrical connections related to the luminaire are secure and properly housed. This is crucial for maintaining the integrity and structural security of lighting installations.

In contrast, the threaded conduit primarily serves as a conduit for electrical wiring and does not provide the same level of support for the luminaire itself. The luminaire, while important for lighting, is the fixture being mounted and does not serve a support function. The electrical feed line delivers power to the luminaire but is not involved in providing structural support. Thus, the T-type conduit body is the component that best fits the description of providing stability and support for luminaires.