Final answer:
Windows Server is classified as a network operating system, which is distinct from RTOS and standalone OS categories.
Step-by-step explanation:
Among the three basic OS categories, Windows Server is neither an RTOS (Real-Time Operating System) nor a standalone OS. It is a network operating system.In contrast to standalone operating systems that are designed for individual devices and user interactions, Windows Server is tailored to support multiple users, applications, and data across a network infrastructure. It excels in managing centralized resources, such as file and print servers, user authentication, and directory services, making it a crucial component in enterprise environments.