Which company is used as an example of a Network Operating System provider?

The correct choice highlights Cisco Systems, Inc., which is well-known for its role as a provider of Network Operating Systems. Cisco specializes in networking hardware, software, and telecommunications equipment, and its operating systems, such as Cisco IOS (Internetwork Operating System), are specifically designed to facilitate communication, management, and security across networks. Cisco's solutions are essential for managing routers and switches, exemplifying how a network operating system functions in real-world applications.

To understand the context of the other companies: Microsoft Corporation is recognized for its operating system and software products, particularly for personal computers and servers, rather than specifically as a network operating system provider, although it does offer server products that include networking capabilities. IBM primarily focuses on enterprise systems, servers, and software, while Apple Inc. is known for its consumer technology and operating systems tailored primarily for personal use rather than for managing network infrastructures. Thus, when it comes to examples of companies that specialize in network operating systems, Cisco stands out.