What characterizes user-level thread management?

User-level thread management is characterized by the fact that applications are responsible for thread management. In this model, the operating system is not directly involved in the scheduling and management of these threads; instead, the user-level library provides the necessary functions to create, manage, and schedule threads.

This arrangement allows applications to have more control over how threads are executed and can lead to performance optimizations as they can use thread management techniques that are tailored to their specific needs. Furthermore, because the kernel does not need to be involved in the context switching among these threads, the application can achieve high performance in managing threads without incurring the overhead that comes with a kernel-managed threading model.

In contrast to this approach, when the operating system manages thread scheduling, it has more control over the execution and resource allocation, which is represented in other options. However, this option indicates that user-level threads allow applications more autonomy, which is a significant characteristic of user-level thread management.