Which of the following best defines mandatory access control $($MAC$)?$Question $47$ options:A$)$ Rights are assigned by a central authority.B$)$ Rights are assigned based on a user's role rather than his or her identity.C$)$ All accounts should be reviewed periodically to ensure that they continue to need the access to resources and privileges they currently hold.D$)$ When accounts are created for temporary employees or access levels are temporarily raised, those accounts should be downgraded or removed promptly.