A fiber optic cable is a physical medium that is capable of conducting
modulated light trasmission. Fiber optic cable carries signals as light waves, thus creating
higher trasmission speeds and greater distances due to less attenuation. This type of
cabling is more difficult to tap than other cabling and is most resistant to interference,
especially EMI.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3:
Telecommunications and Network Security (page 103).

Explanation/Reference:
Sensitivity labels are a preventive security application controls, such as are firewalls, reference monitors, traffic padding, encryption, data classification, one-time passwords, contingency planning, separation of development, application and test environments.
The incorrect answers are:
Detective security controls - Intrusion detection systems (IDS), monitoring activities, and audit trails.
Compensating administrative controls - There no such application control.
Preventive accuracy controls - data checks, forms, custom screens, validity checks, contingency planning, and backups.
Sources:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 7: Applications and Systems Development (page 264).
KRUTZ, Ronald & VINES, Russel, The CISSP Prep Guide: Gold Edition, Wiley Publishing Inc., 2003, Chapter 7: Application Controls, Figure 7.1 (page 360).

Explanation/Reference:
Detective administrative controls warn of administrative control violations. Rotation of duties, required vacations and security reviews and audits are forms of detective administrative controls. Separation of duties is the practice of dividing the steps in a system function among different individuals, so as to keep a single individual from subverting the process, thus a preventive control rather than a detective control.
Source: DUPUIS, Cl?ment, Access Control Systems and Methodology CISSP Open Study Guide, version
1.0 (march 2002).