Which of the following operating systems is based on Unix?

The correct choice is that both Linux and MAC OS X are based on Unix.

Unix is a powerful and influential operating system that has inspired many others. Both Linux and MAC OS X derive aspects of their architecture from Unix, leading to similarities in the way they handle processes, memory management, and file systems.

Linux is a free and open-source operating system that was created with the aim of being similar to Unix, and it uses many of the same principles, which allows it to perform tasks in a manner similar to Unix systems.

MAC OS X, developed by Apple, is built on a Unix-based foundation known as Darwin. This means MAC OS X inherits many of the characteristics and functionalities of Unix, which promotes stability, security, and multitasking capabilities.

In contrast, Windows OS does not have its roots in Unix; it is built on a completely different architecture that does not share the same underlying principles or source code as Unix-based systems. Thus, the most accurate representation is that both Linux and MAC OS X are Unix-derived operating systems.