Final answer:
Linux is an open-source operating system built around the Linux kernel, created as a cost-effective alternative to UNIX, and is employed in a wide range of technology applications, from personal computers to supercomputers.
Step-by-step explanation:
The correct answer to the question is C) Linux - Linux. Linux is a family of free and open-source software operating systems built around the Linux kernel. In 1991, Finnish graduate student Linus Torvalds designed this kernel as an affordable alternative to UNIX. Linux's popularity surged as it allowed for customizable distributions and was freely distributed. This led to a variety of Linux-based OS distributions like Red Hat, Debian, and Ubuntu. Linux also became a prime choice for servers, networking, and as an OS for PCs from companies like IBM and Dell, challenging Microsoft's monopoly. Its capability to rival proprietary supercomputers led to its use in high-performance computing, with all Top-500 supercomputers currently running Linux systems.