Which of the following access control models uses a predefined set of access privileges for an object of a system? Response:

Discretionary Access Control (DAC) allows the owner of a resource to define who can access it and what privileges they have, which is not a predefined, system-wide set of privileges enforced centrally.

Mandatory Access Control (MAC) is an access control model where the operating system or security kernel enforces access rules based on security labels (e.g., classification levels like 'Top Secret') assigned to both subjects (users/processes) and objects (files/resources). Access decisions are made by the system, not the user, according to a predefined set of policies, ensuring strict control over information flow.

"Policy Access Control" is a generic term and not a specific, recognized access control model; all access control models are based on some policy.

Role-Based Access Control (RBAC) assigns permissions to roles, and users acquire those permissions by being assigned to roles; while it uses predefined roles, the question emphasizes "a predefined set of access privileges for an object," which aligns more directly with MAC's label-based enforcement for objects.