Which feature allows an operating system to manage multiple tasks at once?

The feature that enables an operating system to manage multiple tasks simultaneously is multitasking. This allows the OS to execute multiple processes at the same time or switch between them rapidly, giving the illusion that they are running concurrently. Multitasking is fundamental in modern computing, as it enhances user experience by allowing users to run applications such as web browsers, word processors, and games all at once without noticeable delays.

In contrast, single-user operation refers to a system that is designed to be used by one person at a time, but it does not inherently provide the ability to run multiple tasks concurrently, as multitasking does. Device management pertains to how an operating system interacts with hardware devices, optimizing resource usage but not specifically enabling multiple simultaneous tasks. Static resource allocation means that resources are allocated to tasks in a fixed manner, which can limit their ability to handle multiple tasks efficiently. Therefore, multitasking is the key feature that fulfills the need for simultaneous task management in an operating system.