Which of the following operating systems can allow users to have access to the source code, can host various server applications, and can be command line only?

Windows is a proprietary operating system, meaning its source code is not generally accessible to users, and while it can host server applications, its primary deployments typically involve a GUI, although Server Core offers a CLI option.

macOS is a proprietary operating system from Apple, and its source code is not publicly available, nor is it primarily designed or used as a command-line-only server OS.

Linux is an open-source operating system, meaning its source code is freely available to users and developers. It is widely used as a server OS due to its stability, security, and flexibility, and it can be installed and operated purely from a command-line interface (CLI) without a graphical desktop environment.

Chrome OS is based on Linux but is proprietary in its full commercial form, and its primary design is for web-centric consumer devices, not as a command-line-only server operating system with open source code access.