Debian

C.

The correct answer is C. Linux.

Linux is a community-supported, open-source operating system that can be used for both servers and workstations. It is based on the Unix operating system and was first released in 1991 by Linus Torvalds.

Linux is known for its stability, security, and flexibility. It is widely used for web servers, scientific computing, and high-performance computing, among other applications. It is also commonly used as a desktop operating system, especially in the developer community.

One of the key advantages of Linux is that it is open-source, which means that the source code is freely available to anyone who wants to use or modify it. This has led to a large community of developers who work on improving the operating system and creating new applications for it.

Another advantage of Linux is that it is highly customizable. Users can choose from a variety of desktop environments and customize them to suit their preferences. Linux also supports a wide range of hardware, making it a good choice for older or less powerful computers.

In contrast, iOS is a proprietary operating system developed by Apple for use on its mobile devices. Windows 10 is a proprietary operating system developed by Microsoft for use on personal computers. OS X, now known as macOS, is a proprietary operating system developed by Apple for use on its computers.