"Identification is the act of a user professing an identity to a system, usually in the form of a logon ID to the system." Pg 49 Krutz The CISSP Prep Guide.
"Identification describes a method of ensuring that a subject (user, program, or process) is the entity it claims to be. Identification can be provided with the use of a username or account number. To be properly authenticated, the subject is usually required to provide a second piece to the credential set. This piece could be a password, passphrase, cryptographic key, personal identification number (PIN), anatomical attribute, or token." Pg 110 Shon Harris: All-in-One CISSP Certification

Details:
The Answer: Network availability
Network availability can be defined as an area of the Telecommunications and Network
Security domain that directly affects the Information Systems Security tenet of Availability.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 64.

Section: Security Operations

Explanation/Reference:
Explanation:
Preventative Controls. In the Operations Security domain, preventative controls are designed to achieve two things - to lower the amount and impact of unintentional errors that are entering the system, and to prevent unauthorized intruders from internally or externally accessing the system. An example of these controls might be pre-numbered forms, or a data validation and review procedure to prevent duplications.
Incorrect Answers:
A: Detective controls are used to detect an error once it has occurred; they do not prevent unauthorized intruders from internally or externally accessing the system.
C: Corrective controls are implemented to help mitigate the impact of a loss event through data recovery procedures. They do not prevent unauthorized intruders from internally or externally accessing the system.
D: Directive controls are administrative instruments such as policies, procedures, guidelines, and agreements. They do not prevent unauthorized intruders from internally or externally accessing the system.
References:
Krutz, Ronald L. and Russell Dean Vines, The CISSP Prep Guide: Mastering the CISSP and ISSEP Exams, 2nd Edition, Wiley Publishing, Indianapolis, 2004, p. 217.