Filesystems use ACLs to:

Access Control Lists (ACLs) are fundamental security mechanisms used in filesystems to specify which users or groups of users have permission to access certain files and directories. The primary purpose of an ACL is to grant or deny specific privileges—such as read, write, or execute rights—on these resources.

By clearly defining who has access to what, ACLs enable administrators to enforce security policies effectively and control how data is accessed and shared within an organization. This capability is crucial in environments where sensitive information is stored and different users require varying levels of access.

While the other options may touch on related concepts, they either do not accurately represent the function of ACLs or refer to broader or different topics altogether. For instance, dynamic access based on user roles could describe other access control methods but does not specifically address the functionality of ACLs. Monitoring network performance falls entirely outside the realm of file permissions. Defining theoretical access may suggest a concept related to access rights but does not capture the operational aspect of granting or denying access explicitly.