Which of the following access control models requires security clearance for subjects? 

Answer options:

A. Identity-based access control
B. Role-based access control
C. Discretionary access control
D. Mandatory access control

D

With mandatory access control (MAC), the authorization of a subject`s access to an object is dependant upon labels, which indicate the subject`s clearance. Identity-based access control is a type of discretionary access control. A role-based access control is a type of non-discretionary access control. Source: KRUTZ, Ronald L. & VINES, Russel
D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 2: Access control systems (page 33).