Explanation/Reference:
An effective information security policy should be designed with a long-term focus. All other characteristics apply.
Source: ALLEN, Julia H., The CERT Guide to System and Network Security Practices, Addison-Wesley,
2001, Appendix B, Practice-Level Policy Considerations (page 397).

Section: Network and Telecommunications
Explanation/Reference:
It would be correct to select the first answer if the world "security" was not in the question.
Source: TIPTON, Hal, (ISC)2, Introduction to the CISSP Exam presentation.

Section: Access Control
Explanation/Reference:
Capacitance detectors monitor an electrical field surrounding the object being monitored. They are used for spot protection within a few inches of the object, rather than for overall room security monitoring used by wave detectors. Penetration of this field changes the electrical capacitance of the field enough to generate and alarm. Wave pattern motion detectors generate a frequency wave pattern and send an alarm if the pattern is disturbed as it is reflected back to its receiver. Field-powered devices are a type of personnel access control devices. Audio detectors simply monitor a room for any abnormal sound wave generation and trigger an alarm.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 10: Physical security (page 344).

Section: Cryptography
Explanation/Reference:
The Diffie-Hellman algorithm is used for Key agreement (key distribution) and cannot be used to encrypt and decrypt messages.
Source: WALLHOFF, John, CBK#5 Cryptography (CISSP Study Guide), April 2002 (page 4).
Note: key agreement, is different from key exchange, the functionality used by the other asymmetric algorithms.
References:
AIO, third edition Cryptography (Page 632)
AIO, fourth edition Cryptography (Page 709)