What does the Clark-Wilson security model focus on? 

Answer options:

A. Confidentiality
B. Integrity
C. Accountability
D. Availability

B

The Clark-Wilson model addresses integrity. It incorporates mechanisms to enforce internal and external consistency, a separation of duty, and a mandatory integrity policy. Source: KRUTZ, Ronald L. & VINES, Russel
D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 5: Security Architectures and Models (page 205).